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)

Singer Ariana Grande performs during the 2014 MTV Europe Music Awards at the SSE Hydro Arena in Glasgow, on November 9, 2014. (Photo by Toby Melville/Reuters)

The sign above the door of restaurant and hotel “Am Paulusbogen” is partially submerged in the flooded centre of the Bavarian town of Passau, about 200 km (124 miles) north-east of Munich June 3, 2013. (Photo by Michaela Rehle/Reuters)

In this photo taken on Thursday, July 23, 2015 migrants enter a train to Serbia at the railway station in the southern Macedonian town of Gevgelija. The country has become a major transit route for thousands of Middle Eastern and African refugees and migrants who cross over from Greece and then continue into Serbia. (Photo by Boris Grdanoski/AP Photo)

Ice covered leafs are pictured on a tree near Amstall in northern Austria, December 2, 2014. Freezing fog and rain covered parts of the region with ice, causing blocked roads due to fallen trees and closed schools for security reasons, local media report. (Photo by Heinz-Peter Bader/Reuters)

A woman is supported by two men while crossing a river, north of Idomeni, Greece, as migrants attempt to reach Macedonia on a route that would bypass the border fence, Monday, March 14, 2016. Hundreds of migrants and refugees walked out of an overcrowded camp on the Greek-Macedonian border Monday, determined to use a dangerous crossing to head north. (Photo by Vadim Ghirda/AP Photo)

Aerial view of flower fields near the Keukenhof park, also known as the Garden of Europe, in Lisse April 9, 2014. Keukenhof, employing some 30 gardeners, is considered to be the world's largest flower garden displaying millions of flowers every year. (Photo by Yves Herman/Reuters)

Cars at a car dealership are seen in the flooded village of Fischerdorf, near Deggendorf June 7, 2013. REUTERS/Michaela Rehle