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)

Bebe Rexha attends the 61st Annual GRAMMY Awards at Staples Center on February 10, 2019 in Los Angeles, California. (Photo by Rich Fury/Getty Images for The Recording Academy)

This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)

A passenger plane comes into land over a field containing horses at Heathrow Airport on August 11, 2014 in London, England. Heathrow is the busiest airport in the United Kingdom and the third busiest in the world. The airport's operator BAA wants to build a third runway to cope with increased demand. (Photo by Peter Macdiarmid/Getty Images)

This October 25, 2014 photo provided by the U.S. Geological Survey shows lava flow advancing across the pasture between the Pahoa cemetery and Apa'a Street, engulfing a barbed wire fence, near the town of Pahoa on the Big Island of Hawaii. Dozens of residents in this rural area of Hawaii were placed on alert as flowing lava continued to advance. Authorities on Sunday, October 26, 2014 said lava had advanced about 250 yards since Saturday morning and was moving at the rate of about 10 to 15 yards an hour, consistent with its advancement in recent days. The flow front passed through a predominantly Buddhist cemetery, covering grave sites in the mostly rural region of Puna, and was roughly a half-mile from Pahoa Village Road, the main street of Pahoa. (Photo by AP Photo/U.S. Geological Survey)

Curator Anna Reynolds with a doll called Pamela and a toy horse on wheels at the launch of the summer exhibition Royal Childhood at Buckingham Palace, London, which celebrates royal childhood with toys and family gifts belonging to the royal children when they were growing up, on April 2, 2014. (Photo by Sean Dempsey/PA Wire)

“Wernher Magnus Maximilian Freiherr von Braun (March 23, 1912 – June 16, 1977) was a German-born rocket scientist, aerospace engineer, space architect, and one of the leading figures in the development of rocket technology in Nazi Germany during World War II and, subsequently, the United States”. – Wikipedia

Photo: German-born American engineer Dr. Wernher von Braun with a model of the Explorer orbiting space satellite which he designed. (Photo by Keystone/Getty Images). 1958

Three-month old cheetah cubs make their public debut at the Smithsonian National Zoo on July 24, 2012 in Washington, DC. (Photo by T.J. Kirkpatrick)