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)

General view of a clash after the match of the Egyptian Premier League between Pyramids FC and Zamalek at the 30 June Air Defense Stadium in Cairo, Egypt on April 23, 2019. (Photo by Amr Abdallah Dalsh/Reuters)

A man is arrested by Police during clashes in Rotterdam, The Netherlands, 25 January 2021. Police's mobile unit is present and has carried out charges to clear the street. Some arrests have also been made and a water cannon has been used. Nationwide protest against coronavirus restrictions and curfew imposed by Dutch government broke out during the weekend in many Dutch cities, leading to some violent riots and clashes with Police. (Photo by Marco de Swart/EPA/EFE)

An NHS worker walks past a banner supporting NHS staff outside Salford Royal Hospital on March 22, 2020 in Manchester, UK. Coronavirus (COVID-19) has spread to at least 182 countries, claiming over 13,069 lives and infecting more than 308,592 people. There have now been 5,018 diagnosed cases in the UK and 233 deaths. (Photo by Anthony Devlin/Getty Images)

United States' defender Crystal Dunn (R) vies for the ball with Sweden's forward Sofia Jakobsson during the France 2019 Women's World Cup Group F football match between Sweden and USA, on June 20, 2019, at the Oceane Stadium in Le Havre, northwestern France. (Photo by Bernadett Szabo/Reuters)

Marshalls try to get their hands on a streaker as golfers Michael Campbell of New Zealand and Paul McGinley of Ireland play the World Match Play final at Wentworth golf club some 20 miles west of London, 18 September 2005. Campbell won the title at the 17th hole. (Photo by Odd Andersen/AFP Photo)

Mrs. Marie Graskamp of Milwaukee shows the different positions one might assume when entering the bomb shelter in Milwaukee September 3, 1958. This circular entrance is about three feet in diameter. This is the entrance (according to the builders) that would connect to the cellar of a home assuming the shelter was in the ground for added protection. If a bombing should occur, all members of family would proceed to the cellar and then through the circular port into the shelter. (Photo by AP Photo)

The performers prepare for the show. Fontana, a travelling water circus produced by Cirque Du Liban at Festival City in Dubai. (Photo by Chris Whiteoak/The National)