A man sleeps between tombstones in front of his single-room home on a hot night in the Cairo Necropolis, Egypt, October 13, 2015. In the sprawling Cairo Necropolis, known as the City of the Dead, life and death are side by side. Amid a housing crisis in Egypt, and with the population of greater Cairo estimated at about 20 million, people count themselves lucky to have a place to call home in the graveyards that date back hundreds of years. (Photo by Asmaa Waguih/Reuters)

Kale grows at Kajodlingen farm in Gothenburg, Sweden, September 28, 2016. They are doing it on the rooftops, on tower block balconies and even on a disused railway: Swedes have discovered a passion for urban gardening as a way of growing fresh food and getting back in touch with nature. Part of a global movement, an increasing number of Swedish city-dwellers are growing their own in window boxes and allotments or are visiting public gardens built in or on industrial or office spaces. (Photo by Maxim Shemetov/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)

This photo taken on March 29, 2017 shows a young woman offering shots of liquer at a dance bar in Walking Street in Pattaya. Two hours east of Bangkok, Pattaya' s bawdy reputation hails from the Vietnam War era when US GIs partied in their downtime. (Photo by Roberto Schmidt/AFP Photo)

The Rainbow Warrior III, the newest ship of the enivornmental conservation organization Greenpeace, makes its way to port on the Elbe River on October 20, 2011 in Hamburg, Germany. The Rainbow Warrior III, 53 meters long, designed by Greenpeace and built in Poland and Germany, is a EUR 23 million project completed last week. (Photo by Sean Gallup/Getty Images)

The Moonlight Rainbow Fountain is the world's longest bridge fountain that set a Guinness World Record with nearly 10,000 LED nozzles that run along both sides that is 1,140m long, shooting out 190 tons of water per minute. Installed in September 2009 on the Banpo Bridge, former mayor of Seoul Oh Se-hoon declared that the bridge will further beautify the city and showcase Seoul's eco-friendliness, as the water is pumped directly from the river itself and continuously recycled. The bridge has 38 water pumps and 380 nozzles on either side, which draw 190 tons of water per minute from the river 20 meters below the deck, and shoots as far as 43 meters horizontally.

A woman waters the plants outside her house in an alley at a slum in Mumbai October 28, 2014. (Photo by Danish Siddiqui/Reuters)