The longest continuous lava tube in Oregon.

Bridges, terraces, and replicas of historic structures all built of rock and petrified wood by one man.

A sprawling cave network created by a lone lava tube.

While it is not equipped to peer into outer space this observatory looks like it was built on the moon.

The trunks of 3,000 year-old trees lurk beneath the surface of this crystal clear lake in Oregon.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

A giant donut stands as a popular symbol of Los Angeles iconography.

Arcadia is home to a haven for nature geeks and 80s TV lovers alike.

This former stomping grounds of the most eminent astronomers of the early 20th century.

A world-class observatory in the California desert.

North America's largest accredited model railroad museum.

This historic national park is covered in the stunning ruins of red rock pueblos.

The world's largest military aircraft cemetery.

An amazing collection of model trains, collectibles, and artifacts that span the last 100 years.

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.

Limestone caves with spectacular showcase chambers.

Legend says train robbers stashed their gold within the depths of this unusual cave.

Hike the unusual hoodoos and rock formations that form this little-known natural wonder.

This Old West prison built into the side of a cliff was said to be inescapable.

The largest copper mine in Arizona, this enormous open pit emerges from the hills like an alien landscape.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.