Abandoned for over 20 years, this art deco seaside swimming pool is a magnificent waste.

An abandoned anti-smuggling station decays along the boundary between Portugal and Spain.

Founded in 670, this ancient mosque is an architectural time portal.

A statue of Vladimir Illyich Lenin guards this abandoned building in the "Forbidden City."

A subterranean shelter remains intact under a busy Paris railway station.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Abandoned railway line circling the city of Paris.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

Abandoned waterpark turned counter-culture mecca.

The “City of Stairs” sits high in the Andes, above the world’s largest underground copper mine.

The site of one of the largest prison escapes of World War II.

A decommissioned submarine base makes a great space for graffiti art.

This space age health spa looks like a supervillain's lair.

A former French military respite turned jungle tourism hotspot.

These crumbling Latvian forts make for some haunting seaside ruins.

The rusting relics of Southampton's former luxurious flying boat industry.

A graveyard of old and rare planes that once were the glory of Persian aviation.

A vast and unlikely aviation museum kept alive for over 50 years due to one man's tenacity.

This disappearing geyser has been attributed to witchcraft, but really it's all about rainfall.

This colorful creation wasn't always a welcome part of Toronto's Moccasin Trail Park.

This beautiful "lagoon" is actually a toxic soup filled with cars, carcasses, and trash. When warnings couldn't stop people from going for a dip, the town dyed it black.

Journey through the ruins of this ancient Roman temple dedicated to the god of war.