This American Civil War-era fort still stands near the border between Washington, D.C. and Maryland.

A giant mascot, a car bomb, and the mafia mingle in the history of a defunct restaurant chain.

This southwestern historic site was designed and built by an artist who wanted his work to "feel at home."

The first Protestant church in Arizona and only Gothic Revival style adobe church in the world.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

Florence's historic adobe county courthouse was turned into a historic site that honors one of Arizona's most prominent political leaders.

This vintage theme park is peak Christmas kitsch—and it's open all summer.

An urban laboratory.

The exit of the largest prisoner-of-war escape attempt on American soil during World War II.

The unusual burial monument of Arizona's first governor.

A statue based on a tragic Japanese nursery rhyme, commemorating San Diego's sisterhood with Yokohama.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

Nevada's second-newest state park offers camping, fishing, hiking, and river float trips.

The first project by the Bureau of Reclamation illustrates both the upsides and downsides of reclamation.

The gambling entrepreneur who built a city was also an avid collector of classic cars.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

This museum in San Francisco's Chinatown is one of the oldest and largest archives of Chinese American history and culture.

A shining, cold, black organ lies in San Francisco's financial district.

Faceless white figures loom over the city from the rooftop.

Gold Rush ship-turned-hotel buried underneath San Francisco's financial district.

The only theatre in the world constructed specifically for sound movement.

Visible below the waves are memorials to the city's Gold Rush dead.

The only visible piece of San Francisco's most famous shipwreck.

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