A rare surviving Victorian greenhouse designed specifically to house giant water lilies.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

It houses the remains of a 17th-century version of the Titanic.

Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

An illuminated manuscript comprising the life's work of a lone monk, inexplicably decorated with a portrait of Satan himself.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This sublime architectural marvel is a rare example of an expressionist church.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

Museum dedicated to the terror regimes of Hungary.

Budapest's Communist-era statues, banished to the suburbs.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Caves famous for the dragon-slaying saint who lived there.

A trove of ridiculously valuable prints and manuscripts under one roof.

This famous writer's tombstone is a literary pilgrimage site that was publicly defiled by a rival.

A rare, flower-shaped example of Brutalist architecture in Switzerland.

This colorful but controversial ceiling has been likened to a 21st-century Sistine Chapel.

A son-and-daughter meat market, hawked by mom and dad.

China's most famous acrobatics act.

An out-of-place slice of France, smack in the middle of Shanghai.

An collection of Chinese propaganda posters from 1949 to 1979.

Rivers of cattle blood gone, a strange Escheresque building remains, the last of its kind.

This psychedelic tourist trap is a leisurely descent into madness.

This modern castle sat empty for decades before a fire inspired its builders to complete its luxury halls.