In the middle of downtown Brooklyn lies a 165 year old secret hidden right below the surface (closed to the public indefinitely).

An exquisite tunnel of cascading flowers.

Built by one man in the '20s, this site is now a museum representing the Great Basin cultures.

A mysterious castle built as a monument to lost love.

Walk over a 150 year old manhole.

Offbeat arts organization that hosts exhibitions, events, and explorations.

The show pony of cave systems, Fantastic Caverns manages to live up to its name.

A ruined hotel with an unlucky history and an eerie present.

This "zoo" is a cross between a junkyard and a sculpture garden, featuring animals you won't see anywhere else.

A waterfall 600 ft. inside a mountain, once the bane of gold miners, is now a spectacle of nature.

Wee (and not so wee) footprints that insects and reptiles of the Paleozoic Era left behind.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

Obelisks and stone pineapples in the Irish countryside.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.