Performers eat their lunch before the start of the New Year's Day Parade in London, January 1, 2016. (Photo by Kevin Coombs/Reuters)

These are the ambitious plans which suggest skyscrapers of the future may house an entire city. The Endless City project is an award-winning proposal by sure Architecture, who propose turning skyscrapers into complete ecosystems. London is the proposed city for the mixed-use tower – which would feature huge ramps linking different sections of the structure. The company, whose design won the SkyScrapers and SuperSkyScrapers Competition, insist the structure would be a great space-saver in dense cities which have previously spread outwards rather than upwards. (Photo by Caters News)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

A bicyclist with a bike painting on her face rides past the Museum of the Future, in Dubai, United Arab Emirates, Sunday, November 6, 2022. Thousands of people take part in annual Dubai Ride on the skyscraper-lined super highway that cuts through the center of the city. (Photo by Kamran Jebreili/AP Photo)

In the forests of Viiksimo in Finland, in October 2023, a popular spot for watching wolves and bears, a crow has a rival at its lunch spot. (Photo by Valtteri Mulkahainen/Caters News Agency)

Film technicians at Pinewood Studios set up a miniature air crash sequence for the Jack Gold film “The Medusa Touch”, using scale models of a Boeing 747 and a skyscraper. (Photo by Alan F. Davis/Keystone/Getty Images). 9th August 1977

People sit next to a pool where the Tower of Madrid skyscraper is reflected at sunset in Madrid, Thursday, November 26, 2015. The tower was the tallest in Spain since it was finished in 1957 until 1982. (Photo by Francisco Seco/AP Photo)