Subterranean buildings and structures

thumb|right|Tunnel in Col du Galibier, France thumb|right|Tunnel in Fort de Mutzig, France thumb|Decorated portal to a road tunnel in Guanajuato, Mexico thumb|Utility tunnel for heating pipes between [[Rigshospitalet and Amagerværket in Copenhagen, Denmark]] thumb|Tunnel on the Taipei Metro in [[Taiwan]] thumb|Southern portal of the Chirk Tunnel|Chirk canal tunnel, Wales thumb|Victory Tunnel in [[Shimla, India was opened on 08 May 1945 after the Allied victory in World War II]] thumb|Atal Tunnel in [[Himachal Pradesh, India was opened on 4 October 2020 which connects Manali and Keylang, bypass

thumb|A procession in the Pope Callixtus I|San Callistus catacombs in [[Rome, painted by Alberto Pisa]]

thumb|Silver coin from Knossos displaying the 7-course "Classical" design to represent the Labyrinth,

thumb|Chand Baori, in the village of [[Abhaneri near Bandikui, Rajasthan is one of the deepest and largest stepwells in India]] thumb|right|The Rani ki Vav, Patan, Gujarat thumb|upright|A multi-storey stepwell in Mahimapur Village, Amravati District, Maharashtra Stepwells (also known as vav or baori) are wells, cisterns or ponds with a long corridor of steps that descend to the water level. Stepwells played a significant role in defining subterranean architecture in western India from the 7th to the 19th century. Some stepwells are multi-storeyed and can be accessed by a Persian wheel which is

uranium enrichment facility in Iran

nuclear facility in Iran

bomb shelter located beneath Beijing, China

ancient religious monument in Rome, Italy

former missile base of the Soviet Union in Lithuania

air base in Kosovo

naval base in Sweden

hidden infrastructure housing hundreds of Chinese ICBMs

type of underground base in Iran

unfinished Chinese underground nuclear weapons production facility