#9 Turkey’s Underground City
Cappadocia in Turkey is known for its mysterious underground cities. It was created that way to let the people live their lives in total secrecy. The underground cities were built during the Byzantine era where people resided here to protect themselves from the Arab-Byzantine Wars.
A housing construction project helped in the discovery of a complete underground city that is the largest found underground city yet. While the builders were busy demolishing a large number of old buildings in order to construct new urban projects in the city they landed up discovering this invaluable treasure in the city.