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

After a short-lived attempt to bring America in line with the rest of the world, this road was left in metric.

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

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

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

Foragers once flocked to this big beautiful bayou to hunt for pearls.

The only international border marker within the United States.

The U.S. Navy's last diesel-electric submarine rests half-submerged in the middle of Portland.

10,000 flowered plants bloom in the City of Roses.

A Roman-style column in Oregon hides a spiral staircase inside.

100-year-old shipwreck you can walk up to at low tide.

A massive sea stack famous for its appearance in The Goonies.

A logging-themed roadside restaurant surrounded by museum-quality machinery and artifacts from the industry's heyday.

This unassuming cheese empire in rural Oregon churns out more than 150,000 pounds of cheese each day.

The largest wooden building in the world now houses a fascinating collection of aircraft.

Only known mainland rookery of the threatened Stellar sea lion.

This 19th-century museum inside of a lighthouse is only accessible during low tide.

Two mammoth statues inspired by equally tall tales lure tourists to this roadside attraction.

Commonly referred to as the most photographed Victorian home in the United States.

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

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.