This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

A replica of the flagpole that gave a frontier town its name.

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

Less a museum than a bizarre fantasy world created by artists and engineers.

A creepy sculpture of a decapitated head invites viewers to see St. Louis through its empty eyes.

Man-made geyser that rises to the exact height of the Gateway Arch.

Formerly known as National D-Day Museum, this collection commemorates the battles of Normandy and WWII.

The second oldest continuously operating bar in Louisiana.

This cathedral dedicated to Louis IX, sainted King of France, holds many secrets.

A museum and shop on Bourbon Street located in the French Quarter.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

The final resting place of New Orleans' most famous voodoo priestess.

In 2010, Nicolas Cage purchased two plots in this cemetery using one to construct this strange pyramid mausoleum.

A mass grave for victims of an airline disaster that led to much-needed safety improvements for commercial flights.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.

The final resting place for an internet icon.

This memorial pyramid marker honors one of the United States Government's first official camel riders.

This huge dam across the Colorado River caused an armed standoff between two U.S. states.

This once-booming Gold Rush town is now home to a herd of feral donkeys.

More than 25 fully functional scale replicas of famous lighthouses dot the shores of Lake Havasu.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

A sign at the end of the Santa Monica Pier marks the traditional end of the legendary American highway.