The walls of America's oldest masonry fort famously "swallowed" cannonballs.

This headstone-like marker inscribed with three words has been an utter mystery for over a century.

This historic train station has been converted to a locomotive themed hotel.

Walk inside a half mile long crevice right outside the town of Garmisch Partenkirchen.

An effigy of Vancouver's Gastown neighorhood's namesake.

Niagara Falls holds a special place in Nikola Tesla's history, so they put a statue on it.

"Girl in a Wetsuit" is what happens when a sculptor has to find a way around a 100 year old copyright.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

A working steam clock, one of only a few in the world, located in Vancouver's Victorian Gastown.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

This expansive bridge in the Canadian wilderness was originally just built for friends.

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

A music-filled, booze-soaked oasis in the desert.

Ten 25-foot-tall, beehive-shaped kilns, abandoned in Death Valley.

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

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

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

The fifth-longest natural arch in the world, and the longest outside China.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

This erect, phallic geological spire wasn't always named so domestically.

An experimental, automotive replica of Stonehenge.

Yes, this monument is aware that it is about 20 miles away from the actual center of the United States.

A cemetery housing wild west legends in South Dakota.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.