This crumbling stump is all that remains of what was once thought to be the oldest living organism.

The longest living non-clonal organisms on Earth.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

Singing sand that stands as the final remains of an ancient lake.

Officially named the "Loneliest Road in America," this barren stretch of Nevada road offers almost nothing but sky and open fields.

San Francisco's newly reopened hands-on science museum.

Once the largest windmill outside of Holland, with enormous 114 foot sails.

A working model of the entire San Francisco Bay and much of the Sacramento River Delta, complete with regular tides that change every 14 minutes.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A man-made island in scenic San Francisco Bay.

A decommissioned Naval base now rents itself out for people who want to blow stuff up.

Concrete strongholds stand guard over the Golden Gate.

The lighthouse central to the 1980s horror classic "The Fog" is, in fact, located in one of the foggiest areas of the Pacific Coast.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

Inside houses a vast collection of military aircraft and missiles spanning the ages.

This restaurant proudly displays bread signed by the 39th president.

The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

A real flying saucer, contracted by the U.S. Air Force.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

This presidential tomb was not dedicated until years after Harding's death due to personal controversy.

A bronze of the man in all his sinewy glory celebrates his longtime connection to the Ohio city.