Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

A modernist landscape of water and sci-fi concrete.

An emerald-green grotto just a short trip from Austin.

The lowest point in South Dakota and the source of the Minnesota River.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

All that's left of the quintessential "cabin in the woods."

This museum gives tribute to the underappreciated "Down-South Submarine."

You can spend the night as an honorary lighthouse keeper in this quaint, historic beacon.

This natural spring not only claims to heal the wounded but it has also been willed to God.

Amazing pre-Civil War ruins alongside a shallow, rocky river that hosts beautiful (but endangered) lilies.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

A 19th century library favored by Edgar Allan Poe and H.P. Lovecraft, known by locals as "the Ath."

Two massive rock outcroppings on the Oregon coastline.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

A failed piece of Orientalism has become the proud symbol of a community.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

This extravagant Art Nouveau rest stop features a million-dollar view of the Columbia River.

A haunted hot springs hotel that went from healing retreat to asylum before it was restored.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.