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)

A picture rotated 180 degrees shows visitors walking inside an “Upside-down House” attraction at the VVTs the All-Russia Exhibition Center in Moscow, on January 14, 2014. The attraction to experience a new perspective of a house standing upside down was opened first time in Russia, the show organisers said. (Photo by Alexander Nemenov/AFP Photo)

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)

An old toilet is displayed during the “Toilet!? Human Waste and Earth's Future” exhibition at The National Museum of Emerging Science and Innovation – Miraikan on July 1, 2014 in Tokyo, Japan. The exhibition focuses on how the toilet has changed our daily lives and discovers what the most environment-friendly and ideal toilet is. (Photo by Keith Tsuji/Getty Images)

At this year’s Venice Bienniale in Italy, the Korean pavilion has a curious exhibit called “Commissions for Utopia”. It includes renderings from North Korea’s top architects and artists (all anonymous), many of whom studied at the Paekho Institute of Architecture, North Korea’s state-run architectural college, and none of whom have ever left the country. They were asked to create a vision of North Korea’s future sustainable architecture for its expanding tourism industry. Their final products are a glimpse into what it would be like to envision the future after being entirely cut off from the present for almost 70 years. (Photo by Nick Bonner/Kyle Vanhemert/Venice Architecture Biennale)

A model presents the Flesby, a one-seater mobility concept car, during a media preview of the 45th Tokyo Motor Show in Tokyo, Japan on October 25, 2017. Japan's flagship automakers present their futuristic visions for the post-fossil fuel era at the Tokyo Motor Show that kicks off Wednesday. (Photo by Kim Kyung-Hoon/Reuters)

Demonstrators throw fire bombs to riot police during violent protests in central Athens February 12, 2012. (Photo by Milos Bicanski/Getty Images)