People travel by tube on the London Underground to take part in the Pride in London parade, London, Saturday, July 1, 2023. (Photo by Jordan Pettitt/PA Wire via 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)

An injured young woman is led away after an incident at Parsons Green underground tube station in west London on September 15, 2017. Police and ambulance services said they were responding to an “incident” at Parsons Green underground station in west London on Friday, following media reports of an explosion. A Metro. co. uk reporter at the scene was quoted by the paper as saying that a white container exploded on the train and passengers had suffered facial burns. (Photo by Luke MacGregor/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)

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.

Beneath the Swedish capital lies an intricate web of underground train lines. More than 90 of the 100 stations in the 110km tunnel system, sometimes referred to as “the world’s longest art gallery”, have been decorated with paintings, installations, mosaics and sculptures by 150 artists since the 1950s. After spending a couple of weeks exploring arctic Norway and Sweden, London-based travel photographer Conor MacNeill headed underground to capture images of the metro stations. Here: A rainbow arcs over a girl on the platform of Stadion station. (Photo by Conor MacNeill/The Observer)

The series of shots show the bare steel infrastructure of the Bushfield army training camp near Winchester which was in operation during World War Two and was used to train Royal Green Jackets recruits in the sixties. The spectacular images were taken by an urban explorer who wished to remain anonymous. Here: A railway siding in Wiltshire, UK where ammunition was transferred by tunnel to an underground storage facility. (Photo by MediaDrumWorld.com)