A museum dedicated to the alleged Roswell Incident.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

This geothermal hot spring hides beneath a slowly growing mineral dome.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

A modernist landscape of water and sci-fi concrete.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

This naturally-sourced hot spring is now home to a clothing-optional resort.

A self-built castle made by a mysterious man.

This strange seaside tower got its name from a wealthy eccentric who would hide coins among its stones.

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

A breathtaking array of ancient Pueblo structures and artifacts counterintuitively preserved by neglect.

A heavenly experience, right here on Terra Firma.

Odd outsider art installations surround a Gold Rush-era ghost town.

Towering basalt columns, a creation of fire and ice.

A house carved into a rock in the 1940s.

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.

A beautiful 62-acre Catholic shrine and botanical garden.

A hand-built folk art installation covered with messages of God's love.

The ghostly remains of an accidental sea.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

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

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

A trash dump made beautiful by nature's power.