An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

The building features one of the last remaining free-floating spiral grand staircases in the U.S.

City Council meetings still happen in this historic building, impeccably preserved on the inside.

Stroll through a wonderland of stupendous moss-covered trees.

At the most northwestern point of the contiguous United States lies a trail leading through an ancient forest to stunning cliff-side vistas and massive oceanside caves.

A glimpse into the "Logging Capital of the World" at a time when there was far more forest and far less machinery.

One man's eclectic collection of treasures found at sea.

A giant sculpture dedicated to a staple of South Bend food culture.

A tribute to the Nirvana frontman hides beneath the bridge that was the singer's beloved hangout spot.

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

A grave dedicated to the pioneers who settled California.

A unique museum where guests can rent and operate a locomotive.

At the edge of the high desert, California's second-largest natural lake is home to a unique subspecies of trout adapted to its alkaline waters.

The flow from this waterfall sometimes comes out of springs below its rim.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

The long, arduous journey of the stones of the Abbey of New Clairvaux.

Hidden inside a gift shop that doubles as a museum, this gargantuan yo-yo can only be operated by crane.

The oldest orange tree in California spawned a generation of citrus farmers.

California's first suspension bridge.

Mountain known by the Tillamook Tribe as "the place of the supreme deity."

Stepping inside this coffee shop is a journey through time.

Two massive rock outcroppings on the Oregon coastline.

This unassuming cheese empire in rural Oregon churns out more than 150,000 pounds of cheese each day.

Graffiti, cars, and religion combine to create this jungle of scrap in the Nevada desert.