One of the only Florida forts to remain in the hands of the Union all through the Civil War still stands as a historic stronghold.

A monument celebrating the idea of reaching inaccessible places.

A tribute to Ponce de Leon's supposed quest for eternal youth.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

Quirky castle designed by the American actor best known for portraying Sherlock Holmes on stage.

When ecosystems collide in the arid Southwest.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

Thousands of turbines whir at at the origin of North American wind power.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

Four hundred granite steps were built into this massive rock by the National Park Service.

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

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.

Quite simply the largest tree in the world (by volume).

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

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

This quiet park's strange sedimentary spires were named after Kodak's color film.

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

Despite its name, this route in southern Utah offers a heavenly day trip.

Once a menacing challenge for trailblazers, this trail is now the most scenic drive in Utah.

This concert pavilion on the shore of the Great Salt Lake has been destroyed by fire, water, and disinterest but keeps coming back.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."