Places hotcocokitty Wants to Go

The world's only museum devoted to the wonders of fluorescence.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

An unrecognized micronation declared by Greenpeace to protect the glaciers of Chile.

This odd Chilean waterfall-cano hotel must be entered via a rope bridge.

This colorful artistic feature atop a Danish art gallery allows visitors to stroll through a rainbow.

Nearly 40 miles and 1,000 years of limestone mines under Denmark.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

Take a drunken tour inside the world's largest known geode.

A castle built by an eccentric medieval enthusiast in suburban Ohio.

The only remnant of a small mining town is an abandoned railroad tunnel that is steeped in ghostly lore.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

This spacecraft-shaped water tower is only a part of the mysterious UFO mania in this Brazilian town.

This beautiful natural train tunnel is said to grant the wishes of visiting lovebirds.

The largest self-built castle in the U.S., six decades in the making.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

Sleep in a climate-controlled plastic bubble for the night.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

This deceiving white sand beach gets its brilliant hue from the chemical discharge of a nearby factory.

Holy Hindu shrine in an enormous, monkey-filled limestone cavern.

The celebrated eyesore created by starry-eyed sweethearts.

Site of James Cook's historic observations of the 1769 transit of Venus.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.