Hollowed out cedar log tubs set in an ancient towering forest.

A strange house built only at night, with rumored mystic inspiration.

At this Denver landmark, the meals are compulsory, the sopapillas are complimentary, and the insanity is everywhere.

This geothermal hot spring hides beneath a slowly growing mineral dome.

A heavenly experience, right here on Terra Firma.

The world's longest known cave system.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

This frequently-photographed waterfall takes only a short hike to visit.

Florida might be at its most surreal in this museum devoted to the famed Spanish artist.

An underwater city for the dead.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

The "Seinfeld" diner.

This naturally-sourced hot spring is now home to a clothing-optional resort.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

A beautiful geyser under environmental threat.

A self-built castle made by a mysterious man.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

Established in the '60s, a family-owned tropical drink bar founded by Ray Buhen, bartender to the stars.

A pair of slides and a tree-lined stair corridor have been an urban oasis for nearly 40 years.

A beautiful 62-acre Catholic shrine and botanical garden.

Where manatees are the snowbird vacationers in these balmy Florida springs.

This abandoned amusement park was built on a site with a dark history.

The only rotating bar in New Orleans has been slowly spinning since 1949.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.