The largest drain hole in the world.

Remember that scene in the Matrix, when Neo is in the big white room with all the weapons flying by? Well, this is what it would look like if he had wanted trees instead of guns.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Home to the "Circus" trees created by Axel Erlandson.

This woodland architectural installation acts as a camera obscura for the heavens.

Dig for your own trilobites in this goldmine of invertebrates.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

These fantastically named natural pools look like something out of a Scottish myth.

The 953 windows undoubtedly make this the world's most beautiful screened porch.

An outdoor sculpture park of giant pink robots and post-apocalyptic Christmas scenes.

Hundreds of trees made from glass bottles make up this forest on Route 66.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

A nondescript building that's been functioning as a speakeasy for nearly a century and a half.

A semi-scholarly approach to sex.

Home to items never before seen by the public.

A church that bred legends, and served as an inspiration for the Da Vinci Code.

Europe's second largest ossuary wasn't discovered until 2001.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

Experience a quartz crystal sound bath inside a storied, all-wood sound-chamber.

A modernist landscape of water and sci-fi concrete.

San Francisco Bay's ghost town.

A fantastic castle rumored to be the birthplace of King Arthur.

A winding path built in secret on the edge of the continent.