Overview: UNICEF estimates that there may be as many as 100,000 street children in Ukraine. Marcel Theroux and Suemay Oram go underground in Kiev to meet some and find out what their life is like. Ukraine has invested billions in infrastructure projects for the 2012 European football championships. While the fans will enjoy the facilities, most of them won't know that living around them - and beneath their feet under the country's cities - are thousands of young people left on their own to survive dangerous, subterranean lives. Since the break-up of the Soviet Union, years of economic hardship have hurt Ukraine. The result has been a lost generation of teenagers who have run away from broken families, alcoholism and abuse. They suffer awful living conditions and embarrass the Ukrainian government, which in June will host the European Championships as part of its efforts to project a modern, European image with luxury shops and a thriving culture. Many of the teenagers inject drugs or sell sex, and face serious health risks including syphilis, hepatitis, and HIV/AIDS. In some cities, close to 20 per cent of youngsters living on the streets who were tested were HIV positive. Theroux and Oram journey underground through pitch-black basements and passageways under the streets of Kiev. Their guides are a group young people who have made their home at the end of a warren of dark corridors. Outside, the temperature is below minus 20 degrees. Underneath the city's Soviet apartment buildings, hot water pipes are helping keep the street children alive. The team finds 13 who have set up home together, surrounded by mounds of rubbish, which indicate they've been living rough for some time. They've been sniffing glue to take away the feelings of cold and hunger, and the effects are starting to become obvious. Longer-term use causes brain damage. The leader of the group is Vanya, a 29-year-old ex-prisoner. He tells Theroux he can't work because he has no identity papers. They have been stolen and he can't afford the bribes to get new ones. Alongside him is Vova, who has been stabbed but can't afford a doctor. Medical treatment is meant to be free, but hospitals routinely demand payment. Above ground, Kiev's Central Station is a focal point for the city's homeless, who sleep in the waiting rooms and beg outside. Kiev does have shelters for homeless children but many don't want to use them. Theroux meets 14-year-old Dima and his 18-year-old girlfriend Clara. They are living on a set of pipes that carry hot water to nearby apartment blocks. Clara tells Theroux she'd got pregnant from a previous partner, but social services had taken the baby. The spiral of street life is hard to escape, but some do make it out. An hour outside Kiev, Theroux and Oram meet Oksana, who was raised in a state orphanage. After she left it, she lived on the streets and began to drink heavily. She fell pregnant and her daughter was taken away. Then she got pregnant again. But somehow, Oksana tells Theroux, she found the strength to stop drinking. She kept her baby and was eventually reunited with her eldest child. But if she hadn't had help, her children might have ended up on the street themselves. As the Unreported World team leaves Ukraine, Theroux feels like he has witnessed a side of Ukraine that the football fans will never know about: a generation of children who have got lost on the journey from the country's Soviet past to its European future.