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)

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)

Australian singer/songwriter Delta Goodrem comes face-to-face for the first time with a wax figure of herself at Madame Tussauds in Sydney on April 11, 2012. Madame Tussauds, featuring wax doppelgangers of Dannii Minogue, Brad Pitt, Angelina Jolie, Johnny Depp and Lady Gaga, was officially open on April 16. (Photo by Ryan Pierse)

Australian TV personality and singer, Dannii Minogue at the reveal of her wax figure to feature at Madam Tussauds Sydney on February 9, 2012 at the Sofitel, Melbourne, Australia. Madam Tussauds will officially open in Darling Harbour Sydney in May 2012. (Photo by Robert Cianflone/Getty Images)

A man looks at the wax figure of Marilyn Monroe at Grevin Wax Museum in central Seoul, South Korea, July 30, 2015. French wax museum Musee Grevin has opened its first Asian branch in central Seoul with about 80 wax figures including those from hallyu (the Korean pop culture wave) displayed, according to local media. (Photo by Kim Hong-Ji/Reuters)