Underneath the city of Odessa, in Ukraine, is an extensive network of tunnels believed to be the largest catacomb system in the world. Largely unmapped and spread haphazardly under the city, the huge maze of underground passages extends for over 2,500 kilometers. If it were laid out in a straight line the tunnels would reach all the way to Paris. Incidentally, Paris is also the place where the world's second largest catacombs are located. But Odessa’s catacombs are five times longer than those in Paris.

It’s difficult to say when digging underneath Odessa first started but the catacombs were greatly expanded starting from the late 18th century, when Catherine the Great ordered this new port city to be built by the sea. An incredible amount of mining took place to extract limestone to build the city above ground. The tunnels were dug more than a hundred feet below ground on three different levels. New shafts were created whenever old ones ran out of limestone, and it was through this process an intricate web of tunnels began to take shape.

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