These abandoned Cold War-era bunkers are now a designated refuge for endangered bat species.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

Nestled in an unassuming residential area, this "forbidden forest" is rumored to spirit away those who dare enter it.

On Japan's Tashirojima Island, cats are king.

A tangible and sobering reminder of an atrocity that took place during a secret war.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

This infamous prison has a store where you can buy goods crafted by incarcerated people.

Across Ring Mountain is a vast collection of Native American petroglyphs unique to the region.

An ancient Phoenician citadel once stood at the site where Queen Dido first landed, according to legend.

This 170-year-old Swiss guesthouse built into the side of a mountain is best accessed by a cable car.

An architect transformed this abandoned cement factory into his castle-like workshop.

This patch of land is home to Sweden's largest burial mound, allegedly belonging to a mythical king.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A rare pod of derelict midcentury Futuro and Venturo houses lines a semi-abandoned beachfront resort outside Taipei.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

In northeastern Poland, the ruins of a massive granary overlook the Narew River.

The only Bahá'í house of worship in North America and one of only a handful worldwide.

Originally slated to become a luxurious resort, this structure is now a graffiti haunt reclaimed by nature.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

A unique museum dedicated to culture and artistry of carpet weaving.

A star-shaped fortress town fort built in the geometric model of the Renaissance utopian city.

These ruins have been linked to a sherbet factory that exploded, but the story may be entirely fictional.

At the height of alum production at this factory, human urine was a valued commodity.