Underground city

An underground city is a series of linked subterranean spaces that may provide a defensive refuge; a place for living, working or shopping; a transit system; mausolea; wine or storage cellars; cisterns or drainage channels; or several of these.

Underground cities may be currently active modern creations or they may be historic including ancient sites, some of which may be entirely or partially open to the public.

The term may also refer to a network of tunnels that connects buildings beneath street level that may house office blocks, shopping centres, metro stations, theatres, and other attractions.

[1][2][3] Many MTR stations in Hong Kong form extended underground networks connecting to adjecent buildings and at the basement of some major shopping malls in the area above.

In 2005, Westfield Corporation submitted a development application to link Sydney Central Plaza underground with 3 other properties on Pitt Street Mall and extend the tunnel network by a further 500 m (1,640 ft) or more.

The area was and is extensively mined for opal, and the settlers lived underground to escape the scorching daytime heat, often exceeding 40 °C (104 °F).

Melbourne is said to have the largest underground tunnel system in the world spanning over 1,500 km (930 mi), with the clandestine group known as the Cave Clan who meet regularly to explore, vandalise, socialise and map out this network.

[24] In general, many large railway stations house underground hallways featuring shops, restaurants, banks and money exchange offices.

Crystal City in Arlington County, Virginia , an underground city
Shiodome City Center underground in Minato, Tokyo , Japan
Tenjin Underground City in Chūō-ku , Fukuoka , Fukuoka Prefecture , Japan
Tenjin Underground City in Chūō-ku, Fukuoka, Fukuoka Prefecture, Japan
An underground mall in Taipei connecting two Taipei Metro stations
A typical view from inside the underground city in Derinkuyu , one of the largest underground complexes in Cappadocia . There are few artifacts left from the original builders, mainly just large rocks that were used to block the passage for intruders. Most of the "cities" are corridors, but some places there are rooms large enough to live in, and some rooms that have the cross-like shape of a church, which is probably exactly what they were.
A "compass square" of Asematunneli , an underground shopping center near the Helsinki Central railway station
PATH entrance, Toronto , Ontario
Underground passage of the Empire State Plaza , featuring a collection of large-scale abstract modern art
Shirley's White House Vicksburg in 1863