Ukrain'es capital city of Kyiv was built over the Dnieper River & a branching system of tributaries, most of which now run under the streets of the city. I went into the tunnels with a guide for about 3 hours one evening, during which time we saw waterfalls, pipes, memorials to drowned explorers, a few ladders to the surface, and deeply unsettling, dank darkness.

*Apologies for the quality of most of these photos as most were taken with an iPhone. The tunnels are very wet and dark with few places to put down a tripod for long exposures.