more about this conflict is coming up later in the program. europe is in the midst of a deep freeze and belgrade where temperatures have plummeted to minus 20 centigrade is no exception. hawa and his cousin saher are among the estimated 1000 refugees stuck in the serbian capital, trying to survive in desperate conditions. many like them have paid thousands of euros to flee the unrest in their homelands. however, hungary tightened border controls last year and effectively shut down the much used balkan route into mainland europe. returning home to afghanistan would mean facing torture by the taliban. attempting to illegally cross into hungary they say could swiftly end in arrest or beatings by border guards. their only option is to wait. reporter: hawe safe and his cousin saher are desperate to leave. the two afghan refugees are exasperated. they've been stranded in a rundown area just behind

belgrade's central station. over the course of several months, this area has developed into an illegal refugee encampment. today, the serbian government has sent a bus to relocate children and the sick to an official refugee camp. saher: some people going, but say place is full this is problem. reporter: for over 3 months, the two slept in this cark park near the station, at temperatures as low as minus 20 degrees. luxury real estate projects. just a stones throw away afghan and pakistani refugees burn old wooden railroad ties to keep warm. toxic fumes are everywhere. they're waiting to hear from human trafficers at the hungarian and croatian borders if it's worth risking crossing into e.u. territory. but the borders are shut.

some families have paid 5000 euros to send their children to western europe. now, they're stuck in serbia's capital, sheltering in disused warehouses. all they've got left is the hope that they might be able to continue their journey someday. saher and hawe are worn out. they're fed up with living in squalor. saher: yes, yes, going to camp better for me. i'm no problem, one, two months better for me. eating everything available. hawa: i'm in pain. there are metal splinters in my arm from the operation. i need to see a doctor. reporter: hawe says the taliban kidnapped and almost killed him. his arm was broken and he received only very basic medical treatment. he still hopes he can receive medical help in germany. both afghans say there are human trafficers everywhere. opposite them lies luke-djelovic park. those refugees who can afford it are buying hot food.

conspicuously, many of them are checking their smart phones. there are good reasons for this. gordan paunovic knows why, the park's a networking hotspot for trafficers. paunovic runs next door's infopark aid centre which supports many refugees who've been stranded in serbia. gordan paunovic: this park has become a famous smuggler spot. it's the main smugglers hot spot in the whole of serbia. reporter: over the past year, the square's become known as 'afghani park'. there are train and bus stops nearby. gordan paunovic: if you are a new arrival and if you need a contact with the smuggler or you were told by your contact in sofia, in bulgaria or turkey or wherever you are coming from, go to afghani park and find the

grill. this is it, you know, and here you usually have a few guys who can facilitate the continuation of your travel. reporter: the serbian government turns a blind eye. it's glad to see the refugees move on. even though no one says so. ivan miskovic: it is something coped by the ministry of interior in a very successful way. i have to say, because if you look at the official data, official figures, many of them were arrested and processed, so -- but that is the problem of all the countries of the route are fighting with. reporter: but ever since the e.u. countries sealed their borders, serbia has been struggling to cope with the refugees. gordan paunovic: where are you from? >> pakistan. did you just come from the border? where did you go? to croatia? hungary. and how is the situation?

>> the border is too much hard. we can not go, police problem. police hitting us. dog. reporter: this is driving up trafficer's fees for faciliating a border-crossing enroute to western europe. gordan paunovic: how much money to hungary and croatia? how much you need to pay? ungarn: to austria, two thousand euros, without knowing if they'll actually make it across the border. reporter: for hawe and his cousin saher, that's simply too much money. hawe hopes the europeans will recognise that he fled the taliban in afghanistan and grant him asylum. hawa: i hope they'll let me travel to germany legally. i can no longer travel with people smugglers due to my injury. reporter: those who are healthy have a chance of crossing the border. for me, that's impossible.

reporter: serbia has become a dead end for refugees. even for those with a legitimate right to claim asylum in the e.u. >> a few years ago marco streng dropped out of university to become a miner. the 27-year-old went on to found what is said to be the largest mining company of its kind in the world, bitcoin mining that is. the digital online currency is still in its infancy, most commonly used by the most tech savvy amongst us. but its popularity is gaining so much that the online currency has doubled its value relative to the euro over the past year. our reporter traveled across europe to find out what is behind the bitcoin hype. reporter: we're on our way to the annual hackers congress at the parallel polis center in prague. it draws cryptoanarchists from across europe, people who employ encryption technology to keep their internet activity private. the bitcoin is their currency of

choice. at the center's bitcoin coffee bar, you can't buy a drink with regular cash or cards. only bitcoins. so i might as well put my bills away again. but right across the way is an atm which dispenses bitcoins. first i have to download an app to my cell phone, a digital wallet to store my bitcoins. martijn wismeijer explains how easy it is to the use the app. just set it to 'receive', then hold your mobile in front of the atm. within seconds my czech crowns become 6.51 milli-bitcoins. martijn wismeijer: i use a chip implant. i created it in 2014. you can see that tiny little chip. half of it is antenna and the other half is the chip. so if, for example, bitcoins are on here and if i want to buy a red bull, for example there, i can show you. reporter: let's have a look. martin just holds his hand in

front of the machine, and out comes his drink. he says this is the future. martijn wismeijer: you want it again? anybody want some red bull? reporter: martijn says bitcoins are more than digital play money. hundreds of thousands of people use them for everyday transactions, eliminating the need for a regular bank account. martijn wismeijer: i think that banks will always be there. it is just that people have an option now. for the first time in history, this is the first money which is issued by the people and it is owned by the people. there is no banker required. where we are going, there is no banks. reporter: the bitcoin is a currency that's generated on the internet. but how? as i learn here, it's quite simple. to produce a bitcoin, a computer transactions. in return for these services, it's rewarded in bitcoins. this activity is known as 'mining'. but only a maximum of 1800

bitcoins can be generated per day. that's the predefined limit. so the more people are involved in mining for the currency, and the more computers are processing the transactions, the less likely it is that a single computer will be rewarded with bitcoins. so, today, anyone wanting to earn large amounts of bitcoins needs to have huge pools of computers, or mines. competition is becoming fiercer, as there's only a finite and predefined number of bitcoins which can be mined. so the bitcoin works like a precious resource, such as gold. the more people seek to aquire it, the more valuable it becomes. around the world, people are feverishly mining for bitcoins. one of the biggest mines is located in iceland. we're coming in for a landing with bitcoin pioneer marco streng.

he was attracted to iceland mainly because of its geothermal power plants, which produce green electricity from the water of hot springs. he agreed to show us around his mine, provided we don't disclose its exact location. on the drive there, he explains why. marco streng: there's a lot of money involved and many different parties would have an interest in breaking into the mining farm or hacking into it. you can't be careful enough. reporter: from the outside, the hangars look grey and inconspicuous, on purpose. few icelanders are aware that huge amounts of virtual money are produced here every day. inside, it's incredibly loud. reporter: my god, how many machines are there? marco streng: there are over 10,000 graphic cards on this side alone. more than the world's biggest supercomputer. reporter: what do you earn here

per day? marco streng: if i told you that, straight away, all of our competitors could draw a conclusion as to how large we are. in theory, that'd give them a competitive advantage. reporter: roughly. marco streng: i really can't tell you. reporter: what he will tell me is that the electricity bill for his mine is 1 million euros a month. most of that's spent cooling the computer processors. another advantage of being in iceland is that the outside air is reliably chilly. so the climate also helps to keep the hangars cool. in future, marco streng plans to set up new steam-powered mining farms. he believes that in an increasingly uncertain world, the value of the bitcoin can only go one way, up. marco streng: what makes the bitcoin special is this independence from the financial world, and that's almost always the banks.

and, of course, we've seen in the past that this system is, in many places, doomed to failure. reporter: marco streng is even considering building his own geothermal power plant. after all, he's got to invest the money he's earned somewhere. money earned by producing a lot of hot air. >> caomin wu was recently a victim of a wave of unprecedented attacks taking place in france. as a newly arrived immigrant from china, he was beaten up simply because he is chinese. and the alleged aggressors? other immigrants, envious of his perceived wealth and status. young people of north african descent, who make up the largest non-european ethnic group in france, are said to feel a growing resentment towards asian immigrants. and police are often at a loss for how to respond.

reporter: caomin wu lives in a storage depot in the paris suburb of aubervilliers. he doesn't usually talk to journalists but agreed to do so in the presence of two members of the association of chinese immigrants in france. he claims that a group of north african youths attacked him in his home in november. caomin wu: they took a knife and tried to break open the door. reporter: wu tried to resist and incurred a severe head injury. all the rent money for this accommodation block and all cell phones were stolen. wu's wife has since gone to live with relatives. how do you feel now? caomin wu: i'm scared. i don't feel safe anymore. reporter: police registered almost 200 muggings and attacks on the ethnic chinese community of aubervilliers last year. many were reportedly committed

by criminal gangs, often of north african origin. some locals openly voice their prejudices. jugendlicher: that's the way it is. i don't like the chinese, i don't know why but i don't. >> the chinese have become too rich in france. reporter: too rich? and that's not fair? jugendlicher: i think it's not fair. they're now in a category of people with nice clothes and big cars. reporter: the 70,000-strong ethnic chinese community in france has earned a reputation for being hard-working and discrete. the north african communities are considered to be less successful as a whole. guylain chevrier: something new is happening and it's linked to a competitive ideology that's beginning to appear. the chinese are considered to be a community where things go well, where people manage on their own, and are quiet

. compared to other immigrants who are much more demanding and consider themselves as victims and might consider this chinese community as competition. reporter: the chinese textile industry in aubervilliers has grown massively over the past 20 years. and more and more immigrants have come from china to make a better living for themselves in france. wu used to teach geography in china and is a pillar of the chinese community here. he feels let down by the police. caomin wu: my french is not so good so the police did not believe me. those young north africans just claimed that there was a fight between all the people who live

here. but that's not. -- true at all. reporter: the authorities have come under fire for not paying enough attention to inter-communal strife in the suburbs. some sociologists blame the lack of interest on a larger political calculation. the ethnic chinese community tends to vote on the right whereas the north african community is more likely to vote left. guylain chevrier: we're faced with groups that are more and more shaping themselves in terms of identity, especially when it comes to our first community, which we call muslim in inverted commas, that's the way the state identifies and describes it, and this encourages preferential treatment. reporter: there is a suspicion that the authorities' passive attitude has led to an increase in attacks on the ethnic chinese community.

last summer, a man died 5 days after being mugged. yvon sun, president of the chinese association has been trying to persuade families to overcome their shame and to report attacks. a group of youths mugged this girl and threatened her with a knife. yvon sun: i think that the law has to be changed. and the police has to carry out its work. the police do a lot of work in their offices and spend a lot of time on reports, and on complaints. reporter: wu is still waiting for compensation and for his attackers to be put on trial. it could be a long wait. >> while it is vital for

immigrant communities to recognize that by working together they can overcome the obstacles they face, it is even more important for politicians to support this and address the larger structural problems that plague these communities. ♪ >> in the first of our new series, europe's mountains conquering the peaks, we take you to viganella, a village in northern italy which for 3 months every year receives no sunlight. it's not one of those places like the north or south poles, or sweden or norway where in winter, there is continuous night and no day. it is the way the town is situated deep in a valley that it lacks sunlight in the winter months. the sun comes out, but it simply does not shine on them.

but one of the village's residents, pier franco midali, has come up with an ingenious way to shine light into their darkness. reporter: more light. that's what the inhabitants of viganella have always wanted in winter. for three months a year, the village is plunged into darkness and cold. many of the locals can't deal with it so they escape to sunnier spots, leaving houses empty. but there is some help coming from above. where the sun shines. viganella's deputy mayor pier franco midali who is actually a train driver, is committed to bringing light to the village. pier franco midali: we're heading for a rocky promontory well above the village where

there's a mirror. which will beam sunlight straight onto the village square. reporter: it will take an hour to get to the spot. the mirror is in need of new equipment and some repairs. the sides of the antrona valley are so steep that cables, or in the old days mules, are the only way of transporting heavy equipment to the top. a slow, painstaking journey. that's not quite over yet. pier franco has to undertake the final meters on foot. and finally he makes it. he's 1,100 meters above the village which is hidden deep down in the valley. and here's the mirror, measuring five by eight meters in size.

the mayor fulfilled a lifelong dream when he had it installed 10 years ago to bring light to the dark valley, a real technological challenge. pierfranco midali: the material reflects 95% of the sunlight. that's almost all the luminosity. but some of it gets lost because of vapor and dust particles in the air during the refraction. after all, the light does have to travel another kilometer to get to the village. reporter: after installing the control box, they have to check everything is working. the circuits and hydraulic pistons remained broken for two years after a fire damaged the control unit. the mirror was left to its own

devices. the village remained in the dark. but now it's working again and beams sunlight right into viganella. it even illuminates roofs and facades and parts of the village that have never captured the sun before, such as the church's northern side. to the delight of the villagers. gianinno and his wife romina looked forward to this day for a long time. they're so glad to have light again after two dark winters. candida mancini: of course, it's not as powerful as the real sun. it's just a mirror. but we're happy about this for sure. giannino broggio: the light warms my heart. something is happening that i could never have imagined.

romina trischetti: we have to celebrate that fact that we've finally got sun on our piazza in winter. it's wonderful. reporter: but there's still some finetuning to be done. the solar cycle has been saved by the computer which can communicate with the mirror and make adjustments as necessary. pierfranco midali: the mirror moves like the sun but very slowly and in the opposite direction. this way the sunlight is always reflected into the church square. but even this is not enough for midali. he wants to bring sunlight to the darkest corners of viganella. so that the village comes back to life in winter too. pierfranco midali: you have to be a bit crazy, in a positive way, to have new ideas and visions. it helps to break out of this

little world around us. reporter: for now there seems to be no reason why he will not be able to realize his vision and bring light and life to viganella for many winters to come. >> here's hoping that mirror doesn't break down again any time soon. be sure to tune in for our series, europe's mountains conquering the peaks next week where we take you to the swiss alps. let us know what you think about any of our stories, that's it for today. thank you for watching. see you next time. ♪

steves: gibraltar stands like a fortress,

a gateway to the mediterranean. a stubborn little piece of old england, it's one of the last bits of a british empire that at one time controlled a quarter of the planet. the rock itself seems to represent stability and power. and as if to remind visitors that they've left spain and entered the united kingdom, international flights land on this airstrip, which runs along the border. car traffic has to stop for each plane. still, entering gibraltar is far easier today than back when franco blockaded this border. from the late 1960s until the '80s, the only way in was by sea or air. now you just have to wait for the plane to taxi by, and bob's your uncle. the sea once reached these ramparts. a modern development grows into the harbor, and today half the city is built upon reclaimed land. gibraltar's old town is long and skinny, with one main street.

gibraltarians are a proud bunch, remaining steadfastly loyal to britain. its 30,000 residents vote overwhelmingly to continue as a self-governing british dependency. within a generation, the economy has gone from one dominated by the military to one based on tourism. but it's much more than sunburned brits on holiday. gibraltar is a crossroads community with a jumble of muslims, jews, hindus, and italians joining the english, and all crowded together at the base of this mighty rock. with its strategic setting, gibraltar has an illustrious military history, and remnants of its martial past are everywhere. the rock is honeycombed with tunnels. many were blasted out by the brits in napoleonic times. during world war ii, britain drilled 30 more miles of tunnels. the 100-ton gun is one of many cannon that both protected gibraltar and controlled shipping in the strait. a cable car whisks visitors

from downtown to the rock's 14,000-foot summit. from the top of the rock, spain's costa del sol arcs eastward, and 15 miles across the hazy strait of gibraltar, the shores of morocco beckon. these cliffs and those over in africa created what ancient societies in the mediterranean world called the pillars of hercules. for centuries, they were the foreboding gateway to the unknown. descending the rock, whether you like it or not, you'll meet the famous apes of gibraltar. 200 of these mischief-makers entertain tourists. and with all the visitors, they're bold, and they get their way. yeah? you can have it. you can -- you can -- you can -- here on the rock of gibraltar, the locals are very friendly, but give them your apples. legend has it that as long as these apes are here, the british will stay in gibraltar.

eat music) - [voiceover] up next, it's music city roots, live from the factory. in this episode, power folk duo larry campbell and teresa williams, plus bluegrass superbands blue highway and hot rize. that's all ahead, after this. - [voiceover] national broadcast of music city roots is made possible by acceptance auto insurance, based in nashville, tennessee. acceptance offers personal automobile coverage from coast to coast. more information available at acceptance.com. you, your terms, accepted. - [voiceover] franklin, tennessee, inspired music, local flavor, on the edge of nashville. visitfranklin.com. - [voiceover] nissan, proud sponsor of art and culture in our home state of tennessee.

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