I Street Bridge is the heaviest swinging center bridge in the United States.

This museum looks at the history of one of America's most famous prisons and most beloved albums.

One woman's Viking Castle on Lake Tahoe.

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

A volcanic cone that formed over 600 years ago.

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

A glimpse into the lives of the the Miwok and Paiute people in Yosemite National Park.

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

A 19th-century cabin built into a hollowed-out Sequoia tree.

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

One of the last free public hot springs is decorated with hippie art.

This massive redwood tree has a hole in the base big enough to drive through.

A huge musical instrument played by the ocean.

Three hundred years of preserved Spanish colonial history in San Antonio.

Conflicting markers on its floor tell a tale of two city centers in San Antonio.

Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.

A 131-year-old wunderkammer of Texas history.

The quirky gift from West Berlin for the 1968 World's Fair still stands in Hemisfair Park.

Two small markers remember the Alamo's feline protectors.

An abandoned quicksilver mining town surrounded by the Big Bend parks.

An abandoned movie set in the desert of West Texas.

Minimalist modern art on a repurposed military base in rural Texas.

A Prada store in the West Texas desert that is never open for business.

Mysterious glowing orbs float through the desert night.