Beyond being incredibly fun, not much can be said about the Hole with certitude.

A psychedelic labyrinth on the San Francisco bay.

The atmospheric road was never meant to be so creepy.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

The first declared National Monument in the United States.

Rising from the sea like a stone monster.

Stunning wetlands ablaze with pink lotus flowers.

Elevated freight railway turned wildly successful urban park.

New York's oldest magic store.

The only theatre in the world constructed specifically for sound movement.

A 140-year-old castle with underground caves hidden in San Francisco.

An underground mansion with fruit-bearing trees and grapes growing beneath the surface of central California.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

An enormous, inside-out glass globe built in 1935.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

The old Niles Canyon Aqueduct in the San Francisco Bay Area is a bemusing and secret trail through nature for wayward travelers.

A massive underwater sinkhole made famous by Jacques Cousteau.

Dramatic river bend surrounds a natural red-rocked pedestal.

An ancient capital city that dates back 3,000 years old and harbors many surprises.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

On the Oregon coast there is a natural hole that seems to be draining the sea.

Rippling sand dunes frozen in the Arizona rock.

An exquisite tunnel of cascading flowers.

A terrific purveyor of natural history objects and curios.