Las Vegas was once the very definition of a boom town. But the boom went bust and as foreclosures rose, so did the city's homeless population, from 12,000 two years ago to 14,000 today. Yet there are fewer than a thousand beds in shelters, forcing many to seek shelter in the labyrinth of flood tunnels that snake beneath the city.
correspondent Seth Doane
, left, is seen here walking the tunnels with journalist Matt O'Brien, who wrote a book about this elaborate subterranean world.