Female labourers wearing helmets take a break from laying underground electricity cables in Ahmedabad, India, March 7, 2016. (Photo by Amit Dave/Reuters)

A figure of a skeleton is seen painted in a hallway of the house built underground by Manuel Barrantes in San Isidro de Perez Zeledon, Costa Rica, March 14, 2016. Barrantes started digging through red soil and volcanic rock on his farm 12 years ago to build his subterranean house, between 15 and 63 feet (4.57 and 19.2m) underground. The dwelling, which Barrantes says provides a peaceful and comfortable home for him and his family away from noise pollution and the effects of climate change, now covers about 2,000 square feet (185.8 square metres). (Photo by Juan Carlos Ulate/Reuters)

Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)

People walk behind the Medusa head in the Basilica Cistern in Istanbul, Turkey, 24 July 2022. The site has been restored by the Istanbul Metropolitan Municipality and is now open for visitors again. The Byzantine structure was commissioned by Emperor Justinian and built in 532. The underground Basilica, also called Underground Cistern, is the largest well preserved cistern in Istanbul, which rests on a total of 336 columns. According to historical texts, more than 7,000 slaves were involved in the construction of the cistern. (Photo by Sedat Suna/EPA/EFE)

Tami Varma, right, and her brother Robin, the grandchildren of Devendra Varma, a scholar of English gothic tales and an expert in vampire lore, pose in coffins at the Bran Castle, in Bran, Romania, Monday, October 31, 2016. A Canadian brother and sister are passing Halloween night curled up in red velvet coffins in the Transylvanian castle that inspired the Dracula legend, the first time in 70 years anyone has spent the night in the gothic fortress, after they bested 88,000 people who entered a competition hosted by Airbnb to get the chance to dine and sleep at the castle in Romania. A portrait of medieval prince Vlad the Impaler is placed on the wall. (Photo by Vadim Ghirda/AP Photo)

The Lotus Exhibition Center is an icon for the city of Wujin. Conceived as an addition to an existing underground building with a lake top, the center is a sculptural and ethereal lotus flower displaying the three stages of the lotus bloom life.

A man reacts to being warned by a British Transport Police officer for not wearing a face mask at King's Cross underground station, London, England on October 8, 2020. (Photo by Jonathan Brady/PA Images via Getty Images)

Sam Warren climbs in to a prototype combat vehicle during the PrepperCon expo Friday, April 24, 2015, in Sandy, Utah. Hundreds of survivalists and “preppers” are gathering in the Salt Lake City suburb of Sandy for the first annual PrepperCon, featuring demonstrations of underground bunkers, food storage, and armored vehicles. (Photo by Rick Bowmer/AP Photo)