Nasar, an Arabian horse, stands in the office of doctor Stephanie Arndt at her home on February 19, 2014 in Holt, Germany. Fearing for the horse's safety, Mrs. Arndt brought the horse into her house during the Xaver heavy storm back in December, and the horse now wanders through the house daily, inspecting details and looking for snacks. Mrs. Arndt says she doesn't mind, and though the horse never spends the night, it does occasionally take a nap in the house. (Photo by Patrick Lux/Getty Images)

A man admires a sculpture in the series entitled 'Circle of Animals/Zodiac Heads' by Chinese artist Ai Weiwei in the courtyard of Somerset House on May 11, 2011 in London, England. The installation comprises of 12 bronze heads of animals which feature in the Chinese zodiac. The artist Ai Weiwei, who is outspoken in his criticism of the Chinese administration, was detained by authorities in Beijing on April 3, 2011 and his whereabouts remain unknown.

David Nickerson, 28, competes dressed as artist Bob Ross, during the ZJ Boarding House Halloween Surf Contest in Santa Monica, California October 26, 2013. (Photo by Lucy Nicholson/Reuters)

First lady Michelle Obama (R), joined by daughters Sasha Obama (C) and Malia Obama, is presented with the official White House Christmas Tree on November 25, 2011 in Washington, DC. The tree, a 19-foot-tall balsam fir, was grown on Schroeder's Forevergreens farm near Neshkoro, Wisconsin. (Photo by Brendan Hoffman/Getty Images)

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)

Cooperation is key to success. This motto was used by the Government of Denmark when they decided to create a project that bore the name of UN City. This compound was designed to house all nine Copenhagen based UN agencies under a single roof. This embodies the core idea of the United Nations, since this project allows for better efficiency and practicality thanks to joint effort. The first plans for the UN City were hatched in 2002. After 11 years, in 2013 the first stage of the project was finally finished. Presently, Campus 1 of UN City accommodates 1,300 staff member, while Campus 2 is going to become the largest humanitarian warehouse in the whole world.

Students from Langata primary school run past riot police as they protest against a perimeter wall illegally erected by a private developer around their school playground in Kenya's capital Nairobi January 19, 2015. Riot police used teargas to disperse students at a school in Nairobi as the children protested against the potential loss of their playground. The playground was fenced off in December, during the school holidays, by a prominent developer who also claims ownership of the land. The title to the contested site is said to be in the name of Airport View Housing Limited, according to local media, with plans to use the space to build a parking lot for a hotel. (Photo by Thomas Mukoya/Reuters)

Pilots plan a flight manoeuvre with model aircraft at a military air base in Vasylkiv, Ukraine, August 3, 2016. (Photo by Gleb Garanich/Reuters)