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captions paid for by nbc-universal television tonight on the eve of the 9/11 anniversary, we are seeing this place with fresh eyes. no longer the scarred battleground for which the term ground zero seemed so fitting, but rather now, a symbol of rebirth. as a new tower soars into the sky and above a lasting tribute to those we lost. you may not remember exactly what you were doing at this time ten years ago, but most of us could describe the next day in excruciating detail. what we were doing, where we were and what we felt as we watched america under attack. tomorrow, families of the victims will gather here. but today, two other presidents were on hand for the first official 9/11 ceremony. it was held in shanksville, pennsylvania.

940 approximates passengers were remembered for valor and bravery. nbc's tamron hall is there to start us off. good evening. >> i'm standing in what's known as the circle of embrace and inside that circle is now the permanent memorial dedicated to the passengers and crew members on flight 93 and as one family member put it to me today, this is sacred ground that should be protected and respected. >> donald freeman green. >> more than 900 family members and others gather to remember those who died on flight 93. >> no memorial. no words. no acts. can fill a void that they left in your hearts. >> in the background, a simple, but sturdy reminder of the power of standing together. a boulder that now marks the crash site of flight 93, the fourth plane to crash, after the

passengers took a stand against the terrorists. >> what happened above this pennsylvania field ranks among the most courageous acts in american history. the memorial we dedicate today will ensure that our nation always remembers those lost here on 9/11. >> for the families, this has become a place of serenity. >> it's a beautiful place and by being a national park, it will be preserved. >> i could have been consumed with anger and hatred and bitterness. but my brother wouldn't have wanted that. >> the memorial is on 2,200 acres and will be completed in phases. at the ceremony, former president bill clinton announced an effort to speaker boehner for an effort and he spoke of those on the plane. >> they gave the entire country

an uncal gift. they saved the capitol from attack. they saved god knows how many lives. >> for the first time, they read the names of the passengers and crew members etched into an eight-foot granite wall. beyond that wall, hallowed grounds where a nation can come to remember a great sacrifice made by brave americans. tomorrow, president obama will join the family members in a wreath laying ceremony here and then on monday, after ten years, the unidentified remains of some of the victims on that flight will finally be laid to rest. it will be an emotional weekend for these families and they know that the nation is with them. lester? >> tamron hall starting us off from shanksville tonight. thank you. with heightened security in new york today, this were poignant ceremonies across this city ahead of tomorrow's service at ground zero. new yorkers and visitors alike reflecting stories of loss. more from kevin tibbles.

>> reporter: a somber memorial at st. patrick's cathedral for first responders and their families where young patrick lyons read a letter to the father he never met. >> dear dad, i just meeting you. you died on september 11th, 2001. and i was born 26 days later on october 7th. i want you to know that mommy is doing a great job raising me in a happy home. >> a memorial to the 11 lost from this fire house. today, many quietly paid their respects. inside, they will never be forgotten. >> what does this place represent to you? >> it's not a place. it's people. a lot of guys. lost a lot of friends. >> reporter: at the cross roads of the world, times square visitors took time to remember.

>> it's important to be here to stand up with america. >> the fact that all human beings like us that died, we still cherish them. >> reporter: bob morris who worked in law enforcement, is here from utah. >> when one of our brothers get hurt, something happens to them. >> reporter: and on the eve, it's on everyone's mind. >> i think the place is safe. >> reporter: in lower manhattan's battery park, a sea of stars and stripes bear the names of all who were lost. people came hand in hand to stand together. >> this is our home and i think today is the day of solidarity. >> reporter: in bryant park, 2,753 empty chairs for each life lost in new york city. >> these chairs are not just chairs. they're a person. they represent another human being. >> reporter: back at the fire house, another call comes in. here, every day remains a day of

service to the people of this city. and lester, so many of those young first responders that we spoke to today said the reason they decided to serve was because of the sacrifices made by so many ten years ago. lester? >> kevin tibbles tonight, thanks. president obama and the first lady marked this day by visiting arlington national cemetery. the obamas talked with families in section 60, which is reserved for members of the military who have died in those two wars. and shortly after returning from arlington, the president sat down with our brian williams. among other things, they talked about the anniversary of the september 11th attacks. >> we're always struck by how young everybody is there. these kids were in their 20s for the most part and not only are you struck by the incredible

sacrifices made by the fallen, but you have the opportunity to thank directly, young men and women still helping to make america more secure. it's a reminder that our way of life is dependent on the incredible courage, incredible patriotism from a whole host of people, every walk of life, every religion. it's a somber moment when you think about all these young people who gave their life so young. >> much more of brian's exclusive interview tomorrow and monday on "nbc nightly news." also in washington today, a moment of silence for 9/11 victims at the pentagon. before heading to shanksville, former president bush and his wife, laura, placed a wreath at the memorial there. also, leon panetta and donald rumsfeld. now to the show of law

enforcement today in new york and washington. police and federal agents remain on alert taking no chances as investigators look for proof of a possible terror plot involving car or truck bombs. for the latest, we want to turn to our justice correspondent, pete williams, with the latest. >> three days after receiving that second hand report that men were coming here to set off car and truck bombs, the intelligence community has yet to find any indication that there was a real plot behind that tip. traffic on some busy new york streets was choked down to one lane so police could check cars, trucks and vans. as part of a heavily armed show of force. a clearly stepped up police presence in washington, too, and places where tourists gather, including the national mall. >> you just got to go on with business as usual and hope for the best. >> some of this was planned frl 9/11 weekend, but has been tightened up more because of

word that three men flew here to set off vehicle bombs. at a data center in washington, analysts urgently comb through airline passenger records, guided only by vague descriptions by the pakistani source. age, height, travel patterns. complicating the chore is the possibility the men may have been smuggled out of pakistan. hundreds of recent arrivals have been checked and ruled out and around new york and washington, officials say the fbi has found no sign of unusual purchases of chemicals for car bombs. >> we're going to be working this thing for a period of time well after this weekend to make sure we're clear or sure that it was, there was something or not. >> some say if such unverified intelligence came at any other time, it would not generate this response. >> if this was a threat judged

to be two or three months in the future, you would not see so much public attention. but because it's focused on the 9/11 anniversary weekend, it's getting more publicity. >> police are also paying unusual attention to complaint of stolen vans or trucks and here in washington, complaints of strange behavior and suspicious vehicles are up 60% in the last few days. >> and pete, we want to share with our viewers just a little example of the show of force. a line of new york city police cars stretches about a quarter mile long along the west side highway here adjacent to the world trade center. that's the kind of show of force this city is trying to show any potential attackers on this anniversary weekend. let's go overseas now to afghanistan, where the troops are reflecting on the decade gone by. less than a month after 9/11, the u.s. launched operation enduring freedom.

more than 1,700 americans have been killed and as you heard, the president paid tribute to them today. now the men and women who have served for so long are remembering the many sacrifices they've made. we spoke with members of an air force unit in kabul. >> reporter: ten years ago, amber williams was sitting in her sixth grade math class. >> the classroom was quite somber. then the second plane hit. >> reporter: the students were unaware that their lives and the world would soon change. >> i knew as an 11-year-old that what was happening was intentional. >> reporter: some like williams say 9/11 helped them to decide to join the military. others already serving saw their lives and jobs change instantly. >> it affected us job wise, personally and being away from home. >> reporter: these airmen and women assist, train and advise the afghan air force. they believe they've helped make

america safer since 9/11. >> the fact that it's been ten years and we haven't had anything significant. >> reporter: master sergeant joseph fouge trains afghan firefighters. >> we got to finish what we started. >> reporter: still, the separation from his family is difficult. >> i missed my daughter's 16th birthday. i missed her first prom. >> reporter: those serving here say they wish americans could see firsthand the progress they've made. ten years ago, this was a grassy field filled with old soviet tanks and land mines. today, this was built for the afghans so eventually, they can take responsibility for their own security. master sergeant gregory keel says he hopes americans get enough time here to see the mission through. >> our family, we never have to worry about that, but just the support of the american people. i hope they can stick with us. we have to stay the course. >> reporter: ten years after

9/11, america is more secure. but the mission here is unfinished. nbc news, kabul. >> when "nbc nightly news" continues this saturday, the legacy of 9/11. how are our lives changed in the last decade and later, witnesses to history. sewing together a patch work of stories to make sure we never forget.

the changing landscape behind me is vivid testament to our nation's resilience. we took a staggering blow and got back on our feet. still, at times, it seems nothing has been the same since. for months later, we asked, where were you on 9/11? ten years later, the more interesting question is, how did it change you? >> think twice before i get on a plane, subway, train. >> if the '60s robbed us of our innocence, final stole the final shred of security we felt at home. it changed us. >> really changed how we sort of approach the future. >> some things were a given. we knew flying would never be the same for the passengers, but also for the people who flew us. >> one thing i can talk about in general terms is the federal flight deck officer, armed pilots defending the cockpit. >> we also expected there would

be a military response. this, most americans agreed, could not go unpunished. but two wars, one still going ten years later, it's transformed our military and cast a heavy burden on a relative few. >> the young kids and reserve who are frequently older. asked a great deal from them and they've delivered, but after a while, the machine runs out of gas. >> our intelligence agency saw a different world, too. there was patriot act, an intelligence czar, a department of homeland security were added as we wrestled with redefining american justice. >> we have guantanamo. people in detention who are not going to go through civilian courts. we're getting better at understanding how to prosecute individuals. >> i think 9/11 gave way to a lot of prejudices that may not have been there before. >> the killing of bin laden earlier this year answered a

lingering demand for justice, but a would be shoe bomber, an underwear bomber, the slaughter of soldiers at ft. hood, a failed attack on times square, have continued to eat away at our collective security and it has all changed us. in ways both expected and not. >> it brought me closer to my family. >> it made my not sweat the small things. >> we are all one people. it's one world and we have to live in one world. that's my thoughts. thank you. >> reflecting on life after 9/11. we're back in a moment with some of the day's other news.

we're back now with a quick look at some of the other news of the day in northeastern pennsylvania, officials are allowing tens of thousands anxious evacuees to return home to assess the damage as the swollen susquehanna river continues to recede. and our nbc news twitter feed was hacked and the hackers tweeted false information about a plane crash here at ground zero. let's bring in michael isakoff. what can you tell us about this? >> the fbi opened a computer crimes case today in the hacking. the account was hacked late yesterday afternoon with false messages claiming there had be another attack at ground zero. a group known as script kitties is being credited.

they are cyber attackers. they cently took credit for hacking fox news' account. officials believe they send phony e-mails with a special attachment that monitors key strokes. an nbc news employee who overseas the twitter account recently received an e-mail that may have been from the group. within minutes, nbc and twitter worked together to disable the account and spread the word about the hacking incident and false reports, but the damage was done. nbc apologized for the incident, denounced the hacking as wreckless and irresponsible and is working with the fbi in the investigation. >> thank you, michael. up next, weaving together the many stories of 9/11.

finally tonight, the stories of 9/11 and a ground breaking effort to preserve them. as part of the story core audio project, survives and family and friends of those who died interview each other and each recording is archived at the library of congress. tonight, pete has some of the memories. >> reporter: if the soul is contained in the human voice -- >> i miss her eyes. her eyes sparkled to me. >> reporter: then this is how it's preserved for ever. >> i was standing in the middle

of five people and i'm the only one that survived. >> reporter: here in lower manhattan in a small radio booth, hundreds have shared their stories to credit a kind of audio time capsule of memories. >> and made me scared. remember that mikey told me that planes crashed and he wasn't coming back. >> reporter: five years ago, frankirk e and his mom shared their story about his grandfather. she said that experience helped her son heal. >> i just felt so proud, proud that he still had all the memories and got to spend quality time with my dad and not everybody gets that. >> reporter: the goal, to collect at least one story for every person who died that day. beverly remembered her husband.

>> it was about 9:30 and he has been trying to find a way up. i asked if it hurt for him to breathe. he paused and said no. he loved me enough to lie. >> reporter: there are survivor stories, too. amanda spoke about his escape from the north tower. >> the tower had fallen. i thought that was it. i kind of gave up hope. shortly after you called and i picked up the phone and you just said, i'm alive. i get really mad at him, i just think back about the feelings that i had that day. >> reporter: and for those like frankie -- >> if you could talk to him now, what would you want to say? >> i love you and there's no other grandfather. >> reporter: the memories never fade. >> i think about you every day

and you'll always be in my heart forever. >> that's "nbc nightly news" r for this saturday. our special 9/11 coverage begins tomorrow morning at 8:00 eastern time. i'm lester holt reporting from lower manhattan. i'm lester holt reporting from lower manhattan. good night. -- captions by vitac -- www.vitac.com we are just one day away from the tenth anniversary of the september 11th terrorist attacks. good evening,