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)

Penitentes, or nieves penitentes (Spanish for “penitent-shaped snows”), are a snow formation found at high altitudes. They take the form of tall thin blades of hardened snow or ice, closely spaced with the blades oriented towards the general direction of the sun.

Model and Reebok Easytone Ambassador Miranda Kerr reveals a 3D image shot by Rankin during a Reebok Satisfaction photo call on the roof of the Bayerisch Hof Hotel on April 17, 2012 in Munich, Germany. (Photo by Alexander Hassenstein/Reebok)

“The white lion is not a distinct subspecies, but a special morph with a genetic condition, leucism, that causes paler colouration akin to that of the white tiger; the condition is similar to melanism, which causes black panthers”. – Wikipedia

Photo: One of two rare white lion cubs from Mogo Zoo on New South Wales South Coast is seen at a photo call at Lavender Green, Luna Park on November 23, 2006 in Sydney, Australia. (Photo by Matt King/Getty Images)

General view of the entrance to the Swarowski Crystal World museum on its reopening day following renovation, in the western Austrian village of Wattens April 30, 2015. (Photo by Dominic Ebenbichler/Reuters)

Psychotria is a genus containing some 1900 species within the plant family Rubiaceae. Members of the genus are small understorey trees in tropical forests. The former genus Cephaelis is considered a synomym of Psychotria.

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)