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)

Fresh produce and baskets of fish surround a woman at the Siti Khadijah market in Kota Bharu, Malaysia. (Photo by Duratul Ain D.)

The Mount Bromo volcano erupts in the Bryce Canyon, Utah. (Photo by Reynold Dewantara/2016 National Geographic Travel Photographer of the Year Contest)

Visitors dressed in superhero costumes attend the Paris Comics Expo at the Parc Floral in Paris, France, April 15, 2016. (Photo by Charles Platiau/Reuters)

Base jumpers leap from the 300-metre high skydeck of Malaysia's landmark Kuala Lumpur Tower against the backdrop of the city's skyline on October 3, 2016 during the annual International KL Tower Base-Jump event. (Photo by Manan Vatsyayana/AFP Photo)

It's a 30-day-old Echidna baby, known as a “puggle” – one of only 24 ever bred in captivity. The proud parents are Tippy and Pickle of Australia Zoo. The tiny baby, whose s*x has not yet been identified, hatched from a soft egg and will continue to develop and nurse inside Tippy's warm pouch. (Photo by Australia Zoo/Rex/Sipa Press)

Julia Zlobina and Alexei Sitnikov of Azerbaijan gesture as they wait in the results area after competing in the ice dance free dance figure skating finals at the Iceberg Skating Palace during the 2014 Winter Olympics, Monday, February 17, 2014, in Sochi, Russia. (Photo by Vadim Ghirda/AP Photo)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)