This underground city consists of a maze of narrow tunnels, wide chambers, and shallow pools, located about 35 meters beneath the city of Naples in Italy. Its origins date back to the distant past – as far as the 5th century BCE, when the Greeks dug the tunnels with simple tools, and the work continued during Roman times. It took centuries to complete the excavations, and in modern times, these tunnels were used as bomb shelters during World War II. Today, you can tour the tunnels, so if you’re visiting Naples, it’s worth considering this attraction.


These tunnels were dug during the 13th and 14th centuries to provide the residents of Pilsen with a refuge during wars, as well as a place to store food and preserve beer. Above them, there used to be many pubs, some of which served beer inside the tunnels after closing hours. They stretch for about 20 kilometers, though only an 800-meter section is open for tours. Despite the relatively short distance, this section contains 20 different water wells.


This underground city was built to accommodate up to 40% of Beijing’s residents in case of war with Russia. It’s a vast network of tunnels dug across an 85-square-kilometer space during the Cold War, and today, parts of it are open to tourists. Certain sections are even inhabited by millions of people – mostly migrants who came to work in China or students from rural areas living underground in modest conditions. There are over 90 different entrances to this underground city, and surprisingly, it includes a cinema, classrooms, restaurants, and even a barbershop.
Originally a Roman underground city from the 3rd century CE, this is a system of tunnels slowly carved beneath the city of the same name. In the 9th century, Vikings lived there, likely hiding from Christian persecution, and at some point in history, it was home to about 3,000 peasants who even raised livestock and built stables and three churches. During World War I, soldiers also hid there, leaving graffiti on the walls.
This site, nicknamed the "Basilica," is actually a water cistern considered the largest in Istanbul. It was built beneath the palace of the Byzantine emperors, which has not survived to this day, and is supported by 336 marble columns designed in Greek, Corinthian, and Doric styles. One column features carvings that resemble tears, said to be a monument to the hundreds of slaves who died during its construction. Today, the cistern is filled with shallow water, but there’s a low bridge you can walk on.
Located not far from Krakow, these mines are considered among the oldest in the world, operating continuously from the 13th century until the 1990s. There are nearly 3,000 halls and chambers spanning a total length of 300 kilometers, spread across 9 levels with a maximum depth of 327 meters below the surface. Today, the salt mined there is mainly used to create souvenirs for tourists, and visitors can tour 3.5 kilometers of the tunnels, at depths of 64-135 meters underground.
This underground city was carved beneath the city of the same name about 2,500 years ago by Etruscans searching for a water source. The use of the tunnels continued long after the Etruscans left, with each civilization that lived there leaving its mark by digging more tunnels. Now, there are over 1,200 tunnels, and you can visit them as part of a tour organized by the town’s visitor center.
This is the largest underground city among hundreds carved by Christians in the Cappadocia region, where they fled persecution and lived in large families and communities. It’s believed the original caves were dug between the 8th and 7th centuries BCE by residents of the Phrygian kingdom, but Greek-speaking Christians expanded this underground city into what it is today. The city has 20 levels, including a wine press and a church, and could house up to 20,000 people at a depth of 76 meters below the surface.
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