Naturally formed rock city in Poland.

Abandoned substation turned village treasure.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This Parisian café sticks almost exclusively to an ethos of reuse.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

Notorious artist squat renovated into legal studios.

One part local history, 99 parts gruesome haunted house.

The restaurant keeps a hidden séance room on the second floor and reserves a table for the spirit of the former owner each night.

Barcelona's only remaining tram system takes riders to the Tibidabo funicular.

A temple to modernity, tucked away amid Barcelona's more well known museums.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

The music is over at the Ballhaus Riviera Ballroom, but the ballroom remains in haunting disrepair.

A dilapidated psychiatric facility on the outskirts of Milan where electroconvulsive therapy was developed and Napoleon once lived.