This sprawling farm was once a Cold War-era hideaway for the nation's top diplomats.

One of the last active volcanoes on the Eastern seaboard.

An enormous warehouse filled with parade floats collected from over 50 years of patriotic celebrations.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Outsider art meets paleontology at this roadside reptile repository.

An eponymous directional signpost erected by the first president of the United States.

A renovated schoolhouse that highlights the history of Clarke County's Black community.

This striking Victorian Home with its 113-foot turret is best known as the site where abolitionist John Brown was executed in 1859.

Rumors persist that a bottle of whiskey is sealed within this Demijohn-shaped adornment.

This four-story steel sphere in Maryland was used to test biological weapons.

This Maryland farm is known for its amazing corn mazes and its 30-foot junkbots.

An artificial crater field that trained astronauts for lunar exploration.

A mysterious spirit totem at the edge of Navajo lands.

Nature has shaped this drainage tunnel into the digestive tract of a mighty beast.

This unique art installation used boiler tubes from a decommissioned power plant to resemble Antelope Canyon.

These mid-century motels once housed the workers who built the Glen Canyon Dam.

A sharp bend in a dramatic river canyon cut through red rocks.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

More than a century old, this trading post resides in the Navajo Nation.

One of the most extensive and well-preserved collections of dinosaur footprints in North America.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

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

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

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