The Fifteen Billion Pound Railway - Season 1 Episode 3

This episode follows engineers building London's brand new underground railway, Crossrail, as they race to build ten new train stations across London. A team battles to put together the giant jigsaw that will become a cathedral-sized station at Canary Wharf. It's so big, they have to build it in a dock and underwater. Its architect-designed roof is so complicated it comes in a kit of over 2,500 pieces. As engineers carve out the underground caverns that will become the new stations, they hit on some gruesome discoveries of London's past.