Louise Bourgeois' 30-foot-tall steel spider sculpture.

The ruins of the castle that chemicals built.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

Annual Easter display made up of thousands of hand-painted eggs.

A wall of chewing gum moonlights as collective art.

Huge stone depressions which may have acted as an Incan agricultural experiment.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

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

A 90-acre park on former landfill that hosts an annual kite festival.

The World's First 24 Hour Coin-Operated Art Gallery!! Plastic, Styrofoam, and Elvis--If you can't get rid of it, you might as well worship it!!

The magic's in the hole!

Nuclear waste dump site now an environmental sanctuary.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Worker-owned cooperative and resource for those looking to lighten their ecological footprint.

The headquarters of a secretive order is also a beautifully-designed park.

Quite simply the largest tree in the world (by volume).

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

Historic funicular railway, believed to be the shortest railroad in the world.

Sister store to the Echo Park Time Travel Store.

In a city filled with Frank Gehry buildings, one stands out as one of the architect's weirder works.

Perhaps the most unique of any Frank Gehry design for one simple reason: Gehry himself actually lives here.

First LEED-certified gas station in the United States.