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)

Armed women attend a rally to show support to the Houthi movement in Sanaa, Yemen January 13, 2018. (Photo by Khaled Abdullah/Reuters)

Participants lay down on a street covered by coloured powder during the annual Bangkok Color Run in Bangkok, Thailand April 1, 2017. (Photo by Athit Perawongmetha/Reuters)

Romanian female soldiers stand prior to the military parade on Romania's National Day in Bucharest, on December 1, 2022. (Photo by Daniel Mihailescu/AFP Photo)

An alligator devours a fish carcass he stole from a raven in Big Cypress National Preserve in Florida on November 24, 2022. The Big Cypress Swamp is a freshwater swampland located near the Everglades National Park. (Photo by Ronen Tivony/SOPA Images/Rex Features/Shutterstock)

Alfred the frog looks almost as scary as the pumpkin he is perched on at London Zoo 26 October 2011. Keepers at the zoo have joined in the Halloween tradition by supplying pumpkin lunches to some of their animals, including the giant waxy monkey frog. However Alfred is not quite the giant figure his species name suggests – he actually measures up at around 4 inches (10 centimeters). (Photo by EPA/Zoological Society of London)

South Korea's Shim Sukhee falls in the women's 1,500m short track speed skating heat event during the Pyeongchang 2018 Winter Olympic Games, at the Gangneung Ice Arena in Gangneung on February 17, 2018. (Photo by Mladen Antonov/AFP Photo)

Models showcase designs aboard fishing boats off Ngor Island during the 23rd Dakar Fashion Week, organized by Senegalese-French designer Adama N'Diaye, founder of the brand “Adama Paris”, on December 6, 2025, in Dakar, Senegal. (Photo by Cem Ozdel/Anadolu via Getty Images)