In the midst of a living monument to Soviet social engineering, Polish Catholics built this church by hand.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Abandoned concert venue legendary for its rock counterculture.

The avant-garde design was able to bypass strict Soviet regulations on architecture.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

This Detroit ruin was once a gothic bastion of its community, but now it stands as a haunting ruin.

The only surviving prototype of Buckminster Fuller's revolutionary car.

This empty Detroit high school was too expensive to maintain or destroy.

Mai Tais and Navy Grog served up in one of the original tiki bars.

This eerily well-preserved coal town was saved from destruction by a Sean Connery movie.

It's clear this abandoned Art Deco gem was no ordinary cleaners.

One of the most remote and isolated villages on the Arabian Peninsula.

These abandoned waterworks are crumbling into the Potomac River.

This New Orleans statue of a portly figure in a goofy hat pays homage to a classic of satirical literature.

California's own medieval Italian castle, authentic down to the 300-year-old iron maiden in the dungeon.

The medieval-looking hammer beam teak roof may be a Victorian vanity, but it's still absolutely magnificent.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

Henry VIII's forgotten castle was built by the gunpowder-obsessed king to be defended solely by cannons.

Yemen's "Stone Palace" looks like it was carved right out of the tall stone column on which it is built.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

The Brutalist building harbors an unusual inverted dome that swoops down over its central sacred room.

A replica of a 7th-century church hides in plain sight in the middle of the concrete jungle.

This spectacular dome managed to survive after being bombed in World War II, in an event known as the "Miracle of Mosta."