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)

An illuminated Christmas tree leans against the window of a damaged house in Mayschoss in the Ahrtal valley, southern Germany, Tuesday, December 14, 2021. The region was hit by floodings exactly five months ago, causing the death of about 180 people. Amid the mud and debris still clogging the streets from last summer's devastating floods, residents of the Ahr Valley in western Germany are trying to spark some festive cheer with Christmas trees. (Photo by Michael Probst/AP Photo)

An aircraft crosses a bridge over a highway the airport in Frankfurt, Germany, Friday, September 20, 2019. Protests of the “Friday For Futurte” movement against the increase of carbon dioxide emissions are planned Friday in cities around the globe. In the United States more than 800 events were planned Friday, while in Germany more than 400 rallies are expected. (Photo by Michael Probst/AP Photo)

A sеx doll is seen on a bed at the doll brothel “Dollhaus” in Speyer, Germany, 10 December 2018. The “Dollhaus” is the first brothel with sеx dolls only in Germany. The “Dollhaus”, in Speyer, is the brainchild of businessman Raphael Abelmann who says his girls – including ladyboy versions – are the future of the sеx industry. (Photo by Ronald Wittek/EPA/EFE)

An ice swimming enthusiast dressed as Neptune takes to the frigid waters of Orankesee lake during the 27th annual "Winter Swimming in Berlin" on January 8, 2011 in Berlin, Germany. A local swimmers' group called the “Berlin Seals” invite ice swimmers from across Germany and abroad to the annual event. Members claim ice swimming is good for the body's blood circulation. (Photo by Sean Gallup)

An aircraft passes the rising full moon that breaks through the clouds at the airport in Frankfurt, Germany, Monday, March 9, 2020. (Photo by Michael Probst/AP Photo)

An activist is juggling next to police officers at the Dannenrod forest, during a protest of environmentalists against the extension of the A49 motorway, near Dannenrod, Germany, November 27, 2020. (Photo by Kai Pfaffenbach/Reuters)

A GDR Trabant car drives through the city during the local coronavirus disease (COVID-19) lockdown in Dresden, Germany, December 14, 2020. (Photo by Matthias Rietschel/Reuters)