Measuring just five feet at its widest point, the ultra-thin home was unveiled in the Polish capital of Warsaw on Sunday, October 21, 2012. Photo: The Keret House is squeezed into the space between two apartment buildings in Warsaw. There's a four-inch gap between the apartment buildings to either side. A perforated steel facade was used to allow in more light. (Photo by Andrea Meichsner/The New York Times)

The 150-square-metre Villa Ypsilon was designed by London- and Brussels-based firm LASSA, which is headed up by architects Theo Sarantoglou Lalis and Dora Sweijd.

Urban photographer Roman Robroek spent five years scouring the continent for the grandest examples of forgotten architectural beauty. Here: Watch your step on this Polish spiral staircase. (Photo by Roman Robroek/South West News Service)

Candice Swanepoel attends the Victoria's Secret Very s*xy Tour Stop in Dallas at Victoria's Secret Beauty at the NorthPark Mall on March 22, 2012 in Dallas, Texas. (Photo by Peter Larsen/ Getty Images for Victoria's Secret)

Model Amanda Kaspor of Highland, Michigan poses with the CT&T e-Zone Plus electric car is displayed during the press preview for the world automotive media North American International Auto Show at the Cobo Center January 12, 2010 in Detroit, Michigan. (Photo by Bryan Mitchell/Getty Images)

A woman visits a room in a house built upside-down in Russia's Siberian city of Krasnoyarsk, December 14, 2014. The house was constructed as an attraction for local residents and tourists. (Photo by Ilya Naymushin/Reuters)

Colorado Gov. John Hickenlooper shows off his socks--one with Democratic presidential candidate Bernie Sanders and the other with Republican candidate Donald Trump – before entering his former brewpub for a book signing event to mark the release of his autobiography Thursday, May 26, 2016, in Denver. Hickenlooper, who is term-limited, is doing book talk rounds this week, reviving speculation that he is positioning himself to join Hillary Clinton's presidential campaign ticket. (Photo by David Zalubowski/AP Photo)

French photographer Laurent Chehere's “Flying Houses” exhibit takes workaday houses and lets them lift the imagination. The exhibit is showing at the Muriel Guépin Gallery in New York. Photo: Laurent Chehere's “Flying Houses”: “The Great Illusion”. (Photo by Laurent Chehere)