This abandoned secret city is a crumbling wonderland of Soviet ruins.

Thanks to its heroic service during WWII this Soviet castle has been turned into a monument towered over by a brutalist titan.

Ruins of a former government building destroyed during the Georgian-Abkhaz war in the wake of the fall of the Soviet Union.

Pompeii's less famous neighbor is still revealing her secrets.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

An early Portuguese serial killer's head is alarmingly well preserved in a jar at the University of Lisbon.

Abandoned tunnels dug for the once-thriving sea salt industry on the coast of southern Spain.

A wunderkammer of mysterious objects and stories.

Crumbling ruins of the thermal baths that once attracted royals and aristocrats from throughout Europe.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

A forest of immensely tall and unusually straight oak trees planted nearly 200 years ago to build naval ships that never came to be.

A bronze of the man in all his sinewy glory celebrates his longtime connection to the Ohio city.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

Where the writer penned his famous story about a jumping frog.

The nerve center of a massive, state-of-the art radio telescope that sprawls across Western Europe.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.

The gargoyles and grotesques of the 21st century are here—22 emoji built into a new building in the Netherlands.

Lombardy poplars planted to imitate the size and shape of the Cathedral of Notre-Dame de Reims.

The world's largest collection of ships in bottles.

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

An unusual bronze bus shelter is actually an art installation commenting on the city's history with the Nazi party.

A French valley with forests so lush it was nicknamed "the Small Amazonia of the Pyrenees."