This underground metropolis beneath Beijing was constructed in the 1960s as a nuclear war city which occupies over 85 square km.
Now a tourist attraction, it contains granaries, schools, hospitals, restaurants, and entertainment venues, all connected through a network of tunnels and passages.
These tunnels is said to be located beneath the city and reportedly created by Chinese immigrants in Canada as secret shelters during the imposition of the Chinese Head Tax and other regulations.
A labyrinth of bunkers and other structures, all remnants of the Second World War, are tucked beneath Berlin. These hidden locations are currently being investigated and turned into museums that showcase different historical events
In this Italian town which is known for its white wine, exploring the underground corridors offers fascinating tidbits about the lives of the ancient Etruscans.
The people first dug below the surface to construct wells and cisterns, and then they started to make tunnels and galleries.
Without the artistic talent of the miners who worked here and exploited the salt crystal deposits to carve out relief patterns to chandeliers, from chapels to a recreation of Da Vinci's Last Supper, etc. during their free time, this former salt mine would not have attracted attention.
The city is extended across 18 stories and is connected by a network of ventilation shafts, tunnels, and tubes. It is located roughly 60 metres below ground.