This natural marble cave is one of only five national monuments in Oregon.

A Roman-style column in Oregon hides a spiral staircase inside.

A vertically floating hemlock controls the waves and weather at Crater Lake.

A massive sea stack famous for its appearance in The Goonies.

You might know it as the Overlook Hotel, but the inside is not going to be familiar.

Only known mainland rookery of the threatened Stellar sea lion.

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

On the Oregon coast is a natural hole that seems to be draining the sea.

Few things look more out of place than the electric blue ponds in the reddish-brown desert of Utah.

The fifth-longest natural arch in the world, and the longest outside China.

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

Legends surround this jagged rock formation in the New Mexico desert.

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

The largest island on the great salt lake is home to curious creatures and strange stories.

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."

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A huge musical instrument played by the ocean.

This southwest-styled home in Santa Fe claims to be the oldest house in America thanks to an ancient bit of foundation.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

Where layer cakes tower above one’s head and there is never a shortage of icing.