A rich history stashed behind an unassuming door in the heart of Gold Country.

Hidden in a hotel parking lot is a strange historical plaque erected by an obscure fraternal society.

Special tunnels built so that frogs won't be killed when crossing the highway.

Puzzling...this tree looks like an assemblage of dismembered monkey limbs.

For roadside fast food, pull over at the giant orange.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

One of the oldest producers of hand-folded fortune cookies still uses its original secret recipe.

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

This print shop boasts one of the largest pinball arcades in San Francisco.

The rusting remains of the largest assembled WWII fleet on the West Coast.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

The randomness of this wall of lava lamps helps encrypt up to 10 percent of the internet.

Tiki luxury on Nob Hill.

This incredible stone temple is a monument to death, victory, and fantasy architecture.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

One of the oldest student jails in Germany.

It commemorates one of the world's earliest telegraphs.

The largest treasure hoard in Europe is contained in a castle that was bombed out during World War II.

A unique hanging cable-car navigates through Dresden, the oldest suspension railway in the world.

Slaughterhouse Five opens its dank doors to fans of Kurt Vonnegut.

This small exhibition displays equipment and artifacts once belonging to the feared Stasi secret police.

Living trees form the structure of an open-air palace.

This constantly evolving art space saved an Italian town from its own crippling reputation.

A mysterious ancient elephant said to possess magic powers is now the symbol of a Sicilian city.