This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

Described by William Wordsworth as a "World of Wonder."

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

You can row a boat through this ancient underground reservoir.

This museum is a full-size replica of an original church constructed during the 13th-century.

This representation of Lord Vishnu is the largest stone sculpture in Nepal.

An enormous dragon scales the walls of this 17-story temple.

An enchanting work of outsider art, full of whimsical sculptures and carvings.

In addition to fine dairy products, the world's most beautiful milk shop also offers a feast for the eyes.

Where better to stay the night than inside a trio of ancient Chinese deities representing "the good life."

This former lieutenant governor's home is brimming with curiosities.

A lush oasis full of vibrant plants and striking geometric displays.

This once-popular otherworldly landscape was formed by one of the largest volcanic eruptions in history.

Denmark’s never-ending bridge.

This abandoned bridge to nowhere stands secluded in the woods of a Cleveland suburb.

An eerie, existential museum dedicated to the author of "The Metamorphosis."

A submerged village appears when dam levels drop.

The skeletal white beams stand as a monument to religious dissent.

Lost subway station nestled beneath Toronto's busy commuter line.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

An alternate history park where the Union Army loses the war... to dinosaurs.

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

This centuries-old Italian chapel hangs midway down a sheer cliffside.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.