The grand marquee of this abandoned Hawaiian theater remembers the building's elegant past.

Doris Duke's lasting collection of Islamic Art, hidden in a Hawaiian paradise.

Hiding in plane sight.

Hawai'i's oldest wooden house was shipped around Cape Horn from Boston in 1820.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

Race through the maze, get your name on the sign.

This former luxury resort in Kaua'i is now an abandoned relic.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

This picturesque medieval monastery guards a small trove of historic treasures.

This Croatian fairytale castle is slowly falling apart thanks to years of neglect.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

Island wonderland for communist autocrats.

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

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

A musical instrument played by the sea.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

An abandoned brutalist monument whose history has been lost to the ages.

Where the lovelorn find a home for their sentimental keepsakes.

This only museum in the world dedicated solely to mushrooms.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

Crammed into several rooms of a Staten Island home, this museum is a vodka-soaked paean to the pleasures of drinking.

A peculiar museum that includes many drunken tales, a drunk driving simulator, and much more.