captioning funded by cbs and ford. we go further, so you can. >> i'm really excited for this piece. >> what do you know about youtube? did you know that one billion hours of video are watched on it every day, and that it is the most used social network in america. but the site is under increasing scrutiny for objectionable content. >> white lives matter. >> like white supremacy and political misinformation. >> we have been working really hard to figure out what's the right way to balance responsibility with freedom of speech. ( ticking ) >> with the days getting shorter, and temperatures colder, it's sobering to think that on any given night more than half a million americans are homeless. >> oh, boy! >> oh, boy!

>> we went to seattle to see how the city is dealing with homelessness, and find out why so many of its citizens are on the streets. given the work you do, i think most people would think, "well, that's a job that one can live off." >> yeah. i think a lot of people are shocked when they find out that i work full time. >> hey, larry. ( ticking ) >> its not easy to get to... ♪ ♪ ...but for centuries, pilgrims have made their way to a place where faith, mystery and miracles coexist. the story of these 11 ethiopian churches, each carved from a single block of stone, with no brick, no mortar, nor wood, is a creation story you'll need to see to believe. ( ticking ) >> i'm lesley stahl. >> i'm bill whitaker. >> i'm anderson cooper. >> i'm norah o'donnell. >> i'm scott pelley.

those stories tonight, on "60 minutes." ( ticking )

(nicki) hi, everyone. ♪ we just passed the one year anniversary of our 5g launch, so let's think about it... we were the first in the world to launch 5g mobile. we flipped the switch on 14 nfl stadiums and with 5g ultra wideband, we hit over 2 gigabits per second. and we're gonna be in 30 cities by the end of this year. so thank you all. ♪ hbut mike bloomberg became thele clasguy whoho mdid good. after building a business that created thousands of jobs he took charge of a city still reeling from 9/11 a three-term mayor who helped bring it back from the ashes bringing jobs and thousands of affordable housing units with it. after witnessing the terrible toll of gun violence...

he helped create a movement to protect families across america. and stood up to the coal lobby and this administration to protect this planet from climate change. and now, he's taking on... him. to rebuild a country and restore faith in the dream that defines us. where the wealthy will pay more in taxes and the middle class get their fair share. everyone without health insurance can get it and everyone who likes theirs keep it. and where jobs won't just help you get by, but get ahead. and on all those things mike blomberg intends to make good. jobs creator. leader. problem solver. mike bloomberg for president. i'm mike bloomberg and i approve this message.

>> stahl: to grasp the phenomenal scale of youtube, consider that people spend one billion hours watching videos on it-- every day. it is the most used social network in the u.s. more queries are typed into the website's search bar than anywhere online except google, which owns youtube. but the site has come under increasing scrutiny, accused of propagating white supremacy, peddling conspiracies and

profiting from it all. they recently agreed to pay a record $170 million to settle allegations that they targeted children with ads. youtube is being forced to concentrate on cleansing the site. we visited the company's headquarters in san bruno, california, to meet susan wojcicki, the 51-year-old c.e.o., in charge of nurturing the site's creativity, taming the hate and handling the chaos. >> susan wojcicki: we have 500 hours of video uploaded every single minute to youtube. >> stahl: fi-- say that again. >> wojcicki: so, we have 500 hours of video uploaded every minute to youtube. >> stahl: that is breathtaking. >> wojcicki: it is, it is. we have a lot of video. >> stahl: and a lot of influence on our lives, and how we pass our time. ♪ ♪ over a billion people listen to music on youtube every month.

it's the planet's top music site. there's a children's channel with over 44-billion views. ♪ ♪ do you let your children watch youtube, including the young ones? >> wojcicki: so, i allow my younger kids to use youtube kids, but i limit the amount of time that they're on it. i think too much of anything is not a good thing. but there's a lot you can learn on youtube. i think about how youtube in many ways is this global library. you want to see any historical speech, you could see it. you want to be able to learn a language-- >> stahl: make a souffleé? >> wojcicki: you wanna laugh, you just wanna see something funny. you want to do a souffleé! oh, yeah, cooking. cooking's a great example. >> stahl: so is watching people binge eat. >> with the subject ukraine-- >> stahl: a growing number of american adults are turning to it for their news, sports, medical information. it's now mankind's largest "how to" collection.

how to tie a tie, tie the knot, or speak thai. the site has produced whole new pastimes where millions watch strangers open boxes, whisper, sleep. youtube's artificial intelligence algorithms keep recommending new videos so users watch more and more and more. >> wojcicki: happy friday! >> stahl: wojcicki invited us to the weekly all-staff meeting. she's surprisingly down-to-earth for one of the most powerful people in silicon valley, >> wojcicki: and of course we had to have fun. >> stahl: where her trajectory started in an unlikely way. >> wojcicki: i owned a garage. and i was worried about covering the mortgage. so i was willing to rent my garage to any student. but then two students appeared. one was named sergey brin. the other was named larry page. they are the founders of google.

>> stahl: yes, they are. >> wojcicki: but at the time they were just students. they looked like any other students. >> stahl: larry and sergey ended up hiring her as their first marketing manager. she was google employee 16. as the company grew, so did her role, and so did her family. she has five children. google bought youtube on her recommendation, for over $1.6 billion, and eight years later she became c.e.o.-- with a mandate to make it grow and make it profitable. and she did. it's estimated worth is $160- billion. youtube makes most of its money from ads... >> hello, let's do this. >> stahl: ...splitting revenue with people who create all kinds of videos. >> instead of acrylic paint you're going to be using enamel paint. >> stahl: from do-it-yourself lessons, to hip-hop lessons. the more popular ones can become multi-million dollar

entrepreneurs. >> joe biden promised ukraine a billion dollars if they fired the prosecutor investigating his son's company. >> stahl: youtube also makes money from political ads, a thorny issue because some of them have been used to spread lies on social media. facebook is facing a lot of controversy because it refuses to take down a president trump ad about biden which is not true. would you run that ad? >> wojcicki: so that is an ad that, um, right now would not be a violation of our policies. >> stahl: is it on youtube right now? >> wojcicki: it has been on youtube. >> stahl: can a politician lie on youtube? >> wojcicki: for every single video i think it's really important to look at it. politicians are always accusing their opponents of lying. that said, it's not okay to have technically manipulated content that would be misleading. for example, there was a video

uploaded of nancy pelosi. it was slowed down just enough that it was unclear whether or not she was in her full capacity 'cause she was speaking in a slower voice. >> why would i work with you if you're investigating me? >> wojcicki: the title of the video actually said "drunk," had that in the title. and we removed that video. >> stahl: how fast did you remove it? >> wojcicki: very fast. >> stahl: but not completely. we just did a search and there it was still available. the company keeps trying to erase the purported name of the impeachment whistle-blower, but that, too, is still there. which raises doubts about their system's ability to cleanse the site. in the 2016 election cycle, youtube failed to detect russian trolls, who posted over 1,100 videos, almost all meant to influence african-americans-- like this video. >> please don't vote for hillary clinton. she's not our candidate. she's a ( bleep ) old racist

bitch. >> stahl: youtube is an "open platform," meaning anyone can upload a video, and so the site has been used to spread disinformation, vile conspiracies, and hate. this past march a white supremacist live-streamed his killing of dozens of muslims in christchurch, new zealand. he used facebook, but for the next 24 hours copies of that footage were uploaded on youtube tens of thousands of times. >> wojcicki: this event was unique because it was really a made-for-internet type of crisis. every second there was a new upload. and so our teams around the world were working on this to remove this content. we had just never seen such a huge volume. >> stahl: i can only imagine when you became c.e.o. of youtube that you thought, "oh, this is gonna be so fun. it's "people are uploading wonderful things like-- >> wojcicki: funny cat videos.

>> stahl: funny. and look at what we're talking about here. are you worried that these dark things are beginning to define youtube? >> wojcicki: i think it's incredibly important that we have a responsibility framework, and that has been my number one priority. we're removing content that violates our policies. we removed, just in the last quarter, nine million videos. >> stahl: you recently tightened your policy on hate speech. >> wojcicki: uh-huh. >> stahl: why'd you wait so long? >> wojcicki: well, we have had hate policies since the very beginning of youtube. and we-- >> stahl: but pretty ineffective. >> wojcicki: what we really had to do was tighten our enforcement of that to make sure that we were catching everything and we use a combination of people and machines. so, google as a whole has about 10,000 people that are focused on controversial content. >> stahl: i'm told that it is very stressful to be looking at these questionable videos all the time and that there's

actually counselors to make sure that there aren't mental problems with the people who are doing this work. is that true? >> wojcicki: it's a very important area for us. we try to do everything we can to make sure that this is a good work environment. our reviewers work five hours of the eight hours reviewing videos. they have the opportunity to take a break whenever they want. >> stahl: i also heard that these monitors, reviewers, sometimes, they're beginning to buy the conspiracy theories. >> wojcicki: i've definitely heard about that. and we work really hard with all of our reviewers to make sure that, you know, we're providing the right services for them. >> stahl: susan wojcicki showed us two examples of how hard it is to determine what's too hateful or violent to stay on the site. >> wojcicki: so this is a really hard video to watch. >> stahl: really hard. >> wojcicki: and as you can see,

these are prisoners in syria. so you could look at it and say, "well, should this-- it be removed, because it shows violence, it's graphic," but it's actually uploaded by a group that is trying to expose the violence. >> stahl: so she left it up. then she showed us this world war ii video. i mean, it's totally historical footage that you would see on the history channel. but she took it down! why? >> wojcicki: there is this word down here that you'll see, 1418. >> stahl: 1418 is code used by white supremacists to identify one another. >> wojcicki: for every area we work with experts, and we know all the hand signals, the messaging, the flags, the songs, and so, there's quite a lot of context that goes into every single video to be able to understand what are they really trying to say with this video. >> stahl: the struggle for wojcicki is policing the site

while keeping youtube an open platform. >> wojcicki: you can go too far and that can become censorship. and so we have been working really hard to figure out what's the right way to balance responsibility with freedom of speech. >> stahl: but the private sector is not legally beholden to the first amendment. you're not operating under some- - freedom of speech mandate. you get to pick. >> wojcicki: we do. but we think there's a lot of benefit from being able to hear from groups and underrepresented groups that otherwise we never would have heard from. >> but with name calling of nazi or propagandist-- >> stahl: but that means hearing from people with odious messages about gays... >> mr. lispy queer from vox. >> stahl: women... >> sex robots-- >> stahl: and immigrants: >> i think the easiest way for mexicans to not get shot and killed at walmart-- >> stahl: wojcicki explained that videos are allowed as long as they don't cause harm. but her definition of "harm" can seem narrow. >> wojcicki: so if you're saying, "don't hire somebody

because of their race, that's discrimination. and so that would be an example of something that would be a violation against our policies. >> stahl: but if you just said," white people are superior" by itself, that's okay. >> wojcicki: and nothing else, yes. >> stahl: but that is harmful in that it gives white extremists a platform to indoctrinate. >> we want a flourishing, healthy white race. >> stahl: and what about medical quackery on the site? like tumeric can reverse cancer; bleach cures autism; vaccines cause autism. once you watch one of these, youtube's algorithms might recommend you watch similar content. but no matter how harmful or untruthful, youtube can't be held liable for any content, due to a legal protection called" section 230." the law under 230 does not hold you responsible for user- generated content.

but in that you recommend things, sometimes 1,000 times, sometimes 5,000 times. shouldn't you be held responsible for that material, because you recommend it? >> wojcicki: well, our systems wouldn't work without recommending. and so if-- >> stahl: i'm not saying don't recommend. i'm just saying be responsible for when you recommend so many times. >> wojcicki: if we were held liable for every single piece of content that we recommended, we would have to review it. that would mean there'd be a much smaller set of information that people would be finding. much, much smaller. >> stahl: she told us that earlier this year youtube started reprogramming its algorithms in the u.s. to recommend questionable videos much less, and point users who search for that kind of material to authoritative sources, like news clips. with these changes wojcicki says they have cut down the amount of time americans watch controversial content by 70%. would you be able to say to the

public: we are confident we can police our site? >> wojcicki: youtube is always going to be different than something like traditional media where every single piece of content is produced and reviewed. we have an open platform. but i know i can make it better. and that's why i'm here. ( ticking ) >> the debate over section 230, the law that protects tech companies like youtube at 60minutesovertime.com i knew about the tremors. but when i started seeing things, i didn't know what was happening... so i kept it in. he started believing things that weren't true. i knew something was wrong... but i didn't say a word. during the course of their disease around 50% of people with parkinson's may experience hallucinations or delusions. but now, doctors are prescribing nuplazid. the only fda approved medicine... proven to significantly reduce hallucinations and delusions

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>> cooper: with the days getting shorter and the temperatures colder, it's sobering to think that on any given night more than half a million americans are homeless. in the last three years, according to government reports,

cities on the west coast have seen a dramatic rise in the number of people who are "unsheltered." that's the term used to refer to anyone who's homeless, but not sleeping in a shelter. they're the people you see sleeping on streets or in parks, in tent encampments, or in vehicles. why has the unsheltered population been going up at a time of economic expansion and low unemployment? one answer is rising rents in hot real estate markets. take seattle and surrounding king county, which are booming thanks to high-tech companies, but now have the third highest number of homeless people in the country. the seattle area is home to amazon and microsoft, but also to a homeless encampment called tent city three. in the shadow of interstate 5 in seattle, on a vacant strip of public land, this is tent city three. there are about 50 people living here, without heat or running water. that's ethan wood. he's celebrating his third birthday.

he's lived in a tent for the past year and a half. his parents, tricia and josiah, told us ethan has an enlarged heart and suffers from bouts of asthma and croup so severe, they've had to take him to the emergency room several times. last winter, one of seattle's coldest in recent memory, ethan was sleeping in a tent, covered with blankets, sandwiched between his parents for warmth. did you ever think, "well, this is not the place we should have our child?" >> josiah woods: we don't want our son here. we don't want to be here. but as of right now, this is the safest place for us. >> tricia woods: absolutely. >> josiah: because we know the people, we know the rules, and-- >> tricia: our family gets to stay together. >> josiah: and our family stays together. >> cooper: drug addiction is what led the woods to become homeless. for josiah it was meth. for tricia, heroin. they were living in alaska at the time. josiah's parents took care of ethan while they both got treatment.

tricia came to seattle for rehab, and afterwards decided it was a good city for a fresh start. they say they haven't used drugs in nearly two years. but it's been hard to find housing. in may 2018, they tried to get a spot in one of seattle's family shelters, but there was no room. they didn't want to split up into separate shelters-- one for men, and another for women with children-- so they found their way to tent city three, and decided to stay. >> ethan woods: oh, boy. right there. >> tricia: oh, boy. this is our new home. >> cooper: this is one of several makeshift encampments in seattle that are allowed by the city. decisions are made by camp residents, who are also required to do chores and take turns guarding the tents. but about every three months, all the residents in tent city three agree to pack up and move to a new location. it's an arrangement they make with the landowners who let them pitch their tents. no one wants a camp of homeless people in their neighborhood for very long.

>> ethan: here go. >> cooper: when we visited ethan and his parents in september, they had just packed up their tent near the highway and were setting up in a church pastor's back yard. it was the eighth time they've had to move in the past year- and-a-half. someone we talked to said that it-- it's a lot of work being homeless-- that people don't realize that. >> tricia: it is-- it is a ton of work being homeless. >> josiah: it is a lot of work. >> cooper: ex-- explain. >> josiah: we go to a downtown place called urban rest stop for a shower and laundry. >> cooper: how far away is that? >> tricia: from here, that's a 45-minute-- >> josiah: 45-minute bus ride. >> cooper: you take a 45-minute bus ride in order to go take a shower? >> josiah: just to go take a shower. >> tricia: and then wait maybe for 45 minutes to an hour and a half to take that shower. you know, nobody ever plans to live in a tent, ever. so-- >> cooper: you never thought- >> tricia: never. >> josiah: we never thought we'd be here. until something hits you so hard that it just sweeps your feet out from underneath you completely, you can't prepare for it. >> tricia: i used to be one of those people that thought that if anyone was homeless they just needed to go get a job. that would solve their homeless problems. >> cooper: how would you answer that question now? why can't they jge >> tricia: oh, my goodness. maybe they have a job. >> cooper: josiah wood has a full-time job.

he gets up before dawn... and takes mass transit to work as a maintenance supervisor at the hard rock cafeé downtown. though he makes $19.50 an hour, the rent for an average one- bedroom apartment in seattle would eat up half his salary. he and tricia say they've been saving up money so they can afford a security deposit and monthly rent. how long do you think you'll keep living in the tent city? >> tricia: i would hope we are out of here by winter. >> josiah: we will be out of here by winter. i'm not going to allow my family to suffer again in the winter. >> cooper: emilee broll also lives in seattle. she's been delivering mail for the u.s. postal service for nearly five years. >> broll: hey, larry. >> cooper: in her uniform, you'd never know she, too, is unsheltered. she lives in a rickety old r.v. parked by the side of the road, which meets the government's definition of homelessness. more than 2,000 people in the seattle-king county area live in some kind of vehicle.

emilee broll's dodge commander is 42-years-old. why are you living in an r.v.? >> broll: because rent is obscene here. i can't afford it. i just think i'm working my butt off. and i don't want to just spend all of my money paycheck to paycheck just to survive. >> cooper: given the work you do, i think most people would think, "well, that's a job that one can live off." >> broll: yeah. i think a lot of people are shocked when they find out that i'm-- i work full time. >> cooper: what's the solution here? >> broll: affordable housing. build it. quit selling out to developers. >> cooper: housing prices in seattle skyrocketed more than 60% over the last five years as hi-tech companies expanded or moved in. jeff gold was unable to pay the rent on his apartment and was evicted nearly six years ago. when we met him in august, he'd just started a new job as a database coordinator. he was 58-years-old and a graduate of the university of illinois.

this is where jeff was sleeping- - beside a church, on a sheet of cardboard. each morning, he gathered his few possessions, stuffed them in a plastic bag, and stored them in a friend's truck. then he headed for work at the environmental protection agency. do people at work know that you're homeless? >> jeff gold: no. i had a meeting with my boss yesterday and i thought long and hard. like, there was a moment where, like, "should i come out?" >> cooper: during our interview, jeff smelled of liquor, and by his bed, there were empty bottles of vodka-- a step up, he says, from the alcohol he normally would buy with food stamps. how do you get alcohol with food stamps? >> gold: cooking sherry. >> cooper: you can get cooking sherry-- >> gold: it's the only alcohol you can buy on food stamps. >> cooper: do you think you have an addiction issue with alcohol? >> gold: oh, i am definitely an alcoholic. >> cooper: have you tried to stop?

or do you want to stop? >> gold: no. for me, i-- i pretty much have it under control, in the sense that i guess i-- i get to work every morning. >> cooper: i mean, you're sleeping outside on rocks with your possessions in a bag, so it's not all under control. >> gold: i'm movin' forward. i got paid a couple of days ago. >> cooper: in all, there are about 11,000 homeless people in the seattle-king county area, according to the latest government count. they make up roughly 1% of the city's population, but last year they accounted for nearly 20% of those arrested and jailed, mostly for non-violent offenses ranging from theft and loitering to drug violations. >> if property crime is committed, violence is committed, you need to call 911. ( shouting and boos ) >> cooper: at this city council meeting last year, it became clear many residents have had enough. >> we're sick of it! >> ari hoffman: it's out of control. >> cooper: ari hoffman is a seattle businessman and a former candidate for city council. >> hoffman: when you're coming to coach baseball, like i do,

and you have to clean needles off the fields-- >> cooper: you actually have to clean needles off the-- >> hoffman: oh, sure. and there are sometimes people sleeping in the dugouts. >> cooper: what do you think is to blame for it? >> hoffman: you need to stop talking about it like it's a housing affordability issue and start talking about it like it's a drug problem.>> dennis culhann years ago didn't have this level of homelessness. where were these people then? they haven't changed. these folks have been here. >> cooper: dennis culhane, a professor at the university of pennsylvania, has been researching homelessness for 35 years. he doesn't believe drug addiction and mental illness explain why there's been a recent rise in the number of unsheltered people. why is this happening? >> culhane: the best evidence we have is that that's-- it's the real estate market. you have a lot of wealthier individuals, especially in places like seattle, who are driving up the price of housing and there's just not enough housing to filter down to the lower income people. >> cooper: what about substance abuse, alcoholism, drug abuse? >> culhane: substance abuse is particularly important for the people who are homeless for a longer period of time. it's much harder to get out if you have an addiction issue.

>> cooper: professor culhane says most people who become homeless in america are able to get out of it within a few months. but the more than 20% who remain homeless for a year or more are often the most visible, and the vast majority of them do suffer from mental illness, or drug or alcohol addiction. >> mayor jenny durkan: there is hope. we've seen things that actually reduce the number of people experiencing homelessness, but every person takes time-- and you have to have a strategy for that person. >> cooper: jenny durkan is the mayor of seattle. she says the city has added more than 500 shelter spots, taken down more than 1,000 illegal encampments, and secured funding for 5,000 new, affordable housing units over the next three years. the city has also created what they call "enhanced shelters" that try to help people find permanent housing. and mayor durkan is looking for ways to stem the flow of new people who are becoming homeless. >> durkan: too many people come right out of the criminal justice system into

homelessness. and so if you work with the hospitals, the jails, the prisons, foster care system, and say, "let's make sure people have shelter or housing before they go." >> cooper: do you actually feel that the city has a grip on this problem? >> durkan: i think we know what works. >> cooper: i counted 12 people homeless right outside city hall right now. if the city knows what works, why are there still so many homeless people out there? >> durkan: because it's so complex. there's no one city in america that's going to fix this. this has got to be both a regional and state-wide and federal answer. >> cooper: nationwide, there have been successes. since the federal government committed money for housing subsidies and supportive social services for veterans, the number of homeless veterans has gone down 50% in the last ten years. in june, president trump signed an executive order creating a council to come up with ways to cut down on regulations that make it expensive to build affordable housing. but the federal government has not allocated enough housing money to keep up with the crisis.

amazon and its founder jeff bezos have committed more than 300 million dollars to help the homeless in seattle and other parts of the country. apple has pledged $2.5 billion in california. but professor dennis culhane says private donations will only go so far. >> culhane: a billion dollars sounds like a lot, but to solve the housing affordability gap is about a $30 billion requirement. and that's every year. >> cooper: just for housing subsidies. >> culhane: just for housing subsidies. but i should note that we spend about $12 billion a year just on the emergency shelter system, okay, which isn't solving people's homelessness. and even with that expenditure, you know, a third of the people still have no place to sleep. >> cooper: the total number of homeless people in seattle and king county went down by 8% this year according to the city, but there are still more than 5,000 people unsheltered in one of the wealthiest metropolitan areas in the country.

last we heard from jeff gold, he'd been fired from his job at the e.p.a. because of poor attendance. postal worker emilee broll has decided to leave seattle and her r.v. for a place where housing is more affordable. and three-year-old ethan wood? he and his parents are still living in tent city three. they seem no closer to finding a home before winter. >> tricia: nobody really wants to rent to someone who's lived in a tent for the past year regardless of how well of a fit we would be for them. we have absolutely made mistakes in our lives. but that doesn't mean that we don't deserve to raise our family in a house that we can afford. we are more than willing to pay for it. we just need someone to give us a chance to do it. ( ticking ) may 1 of '75...

the magic moment. congress really democratized wall street... i wanted to have a firm that wanted to get everybody in. because people couldn't access wall street. we wanted to be agents of change. for the better. ♪

he borrowed billions donald trump failed as a businessman. and left a trail of bankruptcy and broken promises. he hasn't changed. i started a tiny investment business, and over 27 years, grew it successfully to 36 billion dollars. i'm tom steyer and i approve this message. i'm running for president because unlike other candidates, i can go head to head with donald trump on the economy, and expose him fo what he is: a fraud and a failure. skip to the good part with alka-seltzer plus. now with 25% more concentrated power. nothing works faster for powerful cold relief. oh, what a relief it is! so fast!

hbut mike bloomberg became thele clasguy whoho mdid good. after building a business that created thousands of jobs he took charge of a city still reeling from 9/11 a three-term mayor who helped bring it back from the ashes bringing jobs and thousands of affordable housing units with it. after witnessing the terrible toll of gun violence... he helped create a movement to protect families across america. and stood up to the coal lobby and this administration to protect this planet from climate change. and now, he's taking on... him. to rebuild a country and restore faith in the dream that defines us. where the wealthy will pay more in taxes and the middle class get their fair share. everyone without health insurance can get it and everyone who likes theirs keep it. and where jobs won't just help you get by, but get ahead. mike blomberg intends to make good. jobs creator. leader. problem solver. mike bloomberg for president. i'm mike bloomberg and i approve this message.

( ticking ) >> pelley: if faith is a mystery, there are few places in the christian world where the mystery is deeper than in lalibela. 800 years ago, an ethiopian king ordered a new capital for christians. at 8,000 feet, on the central plateau of ethiopia stand 11 churches, each carved from a single, gigantic, block of stone. no bricks, no mortar, no concrete, no lumber-- just rock sculpted into architecture. t muchs knowabout who built them, or why. but the faithful of the ethiopian orthodox church say there's no mystery really. the churches of lalibela were built by angels. the northern highlands of ethiopia rose 31 million years

ago when fissures in the earth flooded the horn of africa with lava a mile deep. on hillsides you can still see columns of lava frozen in time. iron made the basalt red, and gases trapped inside made the stone light-- as light and pliable as air. christians laid their mark on ethiopia before the year 400. they found the ancient stone welcomed the bite of a chisel. the churches were carved around the year 1200 by people called their king, lalibela, is said to have traveled the 1,600 miles to jerusalem. legend has it, when he returned and jerusalem fell to the islamic conquest, lalibela ordered a new home for christianity. >> fasil giorghis: and he came back with an ambitious idea, a vision of creating an african

jerusalem, a black jerusalem here in the highlands of ethiopia. >> pelley: fasil giorghis is an ethiopian architect and historian who walked us through the rock of ages. >> giorghis: well, there are three groups of churches, and each group is interconnected within itself. >> pelley: we're sitting in saint mary's church. >> giorghis: yes. >> pelley: how was it built? >> giorghis: well, it was built starting from outside. they formed the shape. and then they start digging or excavating downwards. >> pelley: so they dug essentially a trench around the whole perimeter. >> giorghis: yes. >> pelley: which left them with a giant cube of solid rock. >> giorghis: exactly. >> pelley: and then they carved their doors and in they went? >> giorghis: in they went. >> pelley: chipping inside, largely in darkness, artists sculpted many rooms with no room for error. archways, vaults and columns imitate traditional construction even though, in solid rock,

there's no need to hold up the ceiling. the enduring mystery is why. why did king lalibela attempt the seemingly impossible when easier building techniques were known? as the story goes, he was helped by angels. >> giorghis: yes. >> pelley: who worked on the project overnight. >> giorghis: i think i would rather take this as a symbolic thing because-- >> pelley: do you not have any experience working with angels in architecture? >> giorghis: well, i get inspiration from angels. >> pelley: the site of the 11 churches covers about 62 acres. it's divided by a stream king lalibela christened, the river jordan. 0 8,00rgest church covers arount h uaret,ee f fo eur stoacries tall. but their most astounding dimension cannot be measured-- it is the length to which they summon adoration.

>> giorghis: this is considered to be a holy place, that coming here as a devout christian is a very strong sign of their belief. some people travel hundreds of kilometers to get here on foot. on foot. and they have been doing it for several centuries. ♪ ♪ >> pelley: the churches are open for worship year-round but we were there christmas eve when nearly 200,000 pilgrims rose to heaven on a path descending into the earth. many walked for days or weeks, fasting, robed in white-- an ordeal that is rinsed from the disciples in the tradition of jesus. any ethiopian over the age of 30 cannot forget the suffering of drought and war and a million

people lost to starvation. and so, having known poverty in this life, they've invested their souls in the next. tewede yigzaw, told us, "i believe god is here. i came with faith." her neighbor, getaye abebeaw and his daughter told us they walked from their farms nearly 100 miles away-- a journey of three days. god can hear your prayers anywhere. why did you feel you had to be here?" so that god can see our devotion," she said, "and our dedication."" we were very tired," he said," we were falling and getting back up throughout the journey, all to see the celebration here. and god will recognize our effort."

the christmas celebration ethiopians call genna, compresses them-- shoulder to shoulder-- to fast and chant and praise all night 'itil dawn brings christmas day. the ethiopian orthodox church claims to be among the earliest capitals of christianity thanks to a mysterious figure of the hebrew bible. the faithful believe that the queen of sheba left ethiopia, went to jerusalem where she met king solomon. from that meeting came a son, and, when the son was an adult, he returned to ethiopia with 12,000 israelites and the ark of the covenant, containing the tablets with the word of god, the ten commandments. and the ark remains in ethiopia according to the priests of the orthodox church. we met tsigie selassie mezgebu, the head priest of lalibela at

the church of st. george, which was last to be built and judged to be the masterpiece. i met a woman on christmas day who had spent three days walking here. who are these pilgrims?" these are believers," he told us." not just three days, even three months sometimes. ♪ ♪ when there was no air travel or buses, people used to travel from various parts of the country for months, to come here and celebrate with us." the celebration beats to the rhythm of ancient instruments; the kebero doubleheaded drum and a rattle called the sistrum whose sound was known in north africa 3,000 years before jesus. on christmas eve, we watched you

and your priests lead the chant all night long. what are you saying in that chant?" we tell the people that god became human and a human became god. because of christ, we went from being punished by god to being his children again. christmas is the day that forgiveness was born." but, while god forgives, time does not. after eight centuries, the basalt basilicas are weary of wind and water. >> stephen battle: what's absolutely clear is that something quite miraculous happened here. >> pelley: stephen battle is an architect with the world monuments fund, who told us lalibela's miracle is being undermined because thenot ck si. >> battle: when you're building a conventional building, you go to a quarry, and you'll have different grades of stone. and you try and select the best stone.

you leave the bad stuff behind. when you're carving a church out of the mountainside, you don't have that luxury. and so, typically, in any one of the churches here, you get good stone. and a lot of it is good stone. but then you also get actually bad stone and actually very bad stone, which is really very soft indeed. and over time, if you touch it, it actually crumbles. >> simon warrack: and this is one of the most sacred parts of lalibela. >> pelley: we saw the good and the bad in the chamber where king lalibela is laid to rest. this is one of the best- preserved sculptures i've seen at lalibela. >> warrack: yes. this is particularly beautiful. and they're also painted. >> pelley: simon warrack is a master stone mason also with the world monuments fund- a u.s.- based charity that preserves some of humankind's great achievements. warrack has repaired european cathedrals and roman antiquities. but lalibela is more complicated because of the sincere belief

that angels worked this stone. simon, you can't actually cut this stone in order to fit a new piece in, because the stone you would be cutting is sacred. >> warrack: yeah, this was one of the first big issues that i came across. if we ever had to drill a hole to strengthen it to put in a pin, we had to discuss it with the priests. they collected the dust. there was a whole procedure around touching the fabric of the church. >> pelley: the priests collected the dust? >> warrack: yes, yes. >> pelley: that was the issue when warrack was asked to resurrect the cross in this window without disturbing the fragment that remained. so this cross wasn't here. >> warrack: this was completely gone, yes. it was a very thin piece of stone remaining. so i hollowed out the back of the cross shape that we were inserting, so that it was fitting over the original stone, a bit like a, like a dentist. and so we were able to conserve this tiny bit of stone, which

is, in stone masonry terms, it's crazy. but you have to do that in this kind of situation. >> pelley: there have been other crazy conservation ideas. a dozen years ago, five umbrellas were built to keep the heavens from pouring down. >> battle: the local people call them gas station roofs. and i think it's a pretty apt way of describing them. so you can imagine, we have this extraordinary site with some of the most beautiful buildings in the world with extraordinary, huge, spiritual significance. and there's a bunch of gas station roofs that have been placed over the top of them. it's really not compatible, it's not appropriate. >> pelley: unholy to behold, the roofs became a lesson in the law of unintended consequences. the churches were too wet. now they're too dry. for the first time in 900 years, they're not being rained on. >> battle: exactly right. and so the stone is contracting much more than it has ever done before. and what happens ies little failures on a micro level and the stone starts to crumble.

>> pelley: the roofs were meant to be temporary and in a few years they must be recovered. stephen battle prays they'll be removed altogether and replaced by intensive maintenance. to that end, the world monuments fund is teaching conservation to dozens of lalibela's priests and laymen in the hope that a host can protect the heavenly perhaps for centuries to come. how long can they last? >> battle: well, another 900 years, if they're looked after properly. oh, yes, way beyond a shadow of a doubt, absolutely, if they're looked after correctly. >> pelley: even beyond another millennia we're not likely to know with certainty the answer to why. why attempt what must have seemed impossible? no answer was apparent until we chipped away at what we saw christmas day. in the old testament, isaiah

advises those who seek god to," look to the rock from which you were cut and the quarry from which you were hewn." whoever cut this rock, angels or man, understood that in the presence of a miracle, faith is never washed away. ( ticking ) >> cbs sports hq is presented by progressive insurance. i'm james brown with the scoors from the n.f.l. today. pittsburgh takes the rematch as devlin hodges wins his second straight start. baltimore wins its eighth in a reon a game-winning field goal. tennessee scores 24 unanswered. green bay wins behind four aaron rodgers tv passes. cincinnati griewdz the -- grounds the jets for its first win this season.

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we don't see who you're against, through or for,rs, whether tomorrow will be light or dark, all we see in you, is a spark we see your spark in each nod, each smile, we see sparks in every aisle. we see you find a hidden gem, and buying diapers at 3am. we see your kindness and humanity. the strength of each community. we've seen more sparks than we can say. about 20 million just yesterday. the more we look the more we find, the sparks that make america shine.

( ticking ) >> whitaker: i'm bill whitaker. stick around. your holiday travels may be over, but we've got some more places to visit.

we'll be back in a few minutes on this thanksgiving weekend with a second helping of "60 minutes." we ordered 10,000 units. that sounds good. pretty cool, huh? they're speaking to mom in japanese, and mom hears them in english. ♪

can you understand me? yes, i can understand you. okay. i have a lot of questions. how do you guys fly? what does santa do in the summer? is mrs. claus a good cook? do you guys get presents? can you roller skate or ice skate?

( ticking ) captioning funded by cbs and ford. we go further, so you can. captioned by media access group at wgbh access.wgbh.org captioning funded by cbs and ford. we go further, so you can. >> tonight on this special edition of "60 minutes presents: great adventures." travel as deep into the earth as man has ever traveled, two miles down, to get to the rock that's become this: liquid molten gold. but gold's not all, scientists have found something else down there-- something known as extreme light. which might also exist on mars. so the martians we meet in the future-- >> be prepared to be surprised, i would say. ( ticking ) >> in mongolia, hunters partner with eagles, in a tradition that goes back thousands of years.