Stunning silhouettes under European cities reveal the size and splendor of the continent’s urban foundations. Photographer and content-manager Anna Arinova, 28, from Moscow, captured the awe-inspiring labyrinths in Russia and Germany. Here: Regenwurmlager, Poland. The Regenwurmlager is an extensive underground fortification area constructed by Germany in 1920s-1940s, now in western Poland, near the city of Międzyrzecz. (Photo by Anna Arinova/Caters News)

Excited Brits beamed as they grabbed a pint outside in Leeds, United Kingdom on April 17, 2021. Pubs and restaurants with outdoor space have been allowed to reopen as lockdown restrictions are eased in the UK. (Photo by Nb press ltd)

Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

A mass pillow fight in Trafalgar Square in central London on April 5, 2014 on International Pillow Fight Day. (Photo by Jane Scanlan)

Children wearing uniforms hold toy guns during a military parade game on China's National Day, at Beyou World, a centre children where can experience different kinds of professions, in Beijing, October 1, 2015. (Photo by Reuters/Stringer)

A performer blows fire during Chinese Lunar New Year celebrations in Chinatown, Binondo, Manila, Philippines, January 25, 2020. (Photo by Eloisa Lopez/Reuters)

Garrett Gerloff (L) of the USA GRT Yamaha WorldSBK Junior Team and Sandro Cortese (R) of Germany on OUTDO Kawasaki TPR colide during a warm up session of the the World Superbike Championship on Phillip Island, Victoria, Australia, 01 March 2020. (Photo by Scott Barbour/EPA/EFE)

The erupting Litli-Hrútur volcano on the Reykjanes Peninsula in Iceland captured with a drone in the last decade of July 2023. (Photo by Elliot McGucken/Animal News Agency)