A walk through the historic city center, under the streets of Seattle.

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

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

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

Two massive rock outcroppings on the Oregon coastline.

Only known mainland rookery of the threatened Stellar sea lion.

The park preserves a single, rare species of carnivorous plant that spells doom for unsuspecting insects.

According to legend, this rock represents a young girl trapped by an evil ocean spirit.

This 19th-century museum inside of a lighthouse is only accessible during low tide.

Pillars made of 700 pieces of luggage climb to the ceiling of Sacramento Airport's baggage claim.

I Street Bridge is the heaviest swinging center bridge in the United States.

A replica of the first public theater built in California.

The California capital city once stood 10 feet lower than it does today.

Art Deco stylings conceal the true nature of this bridge.

The tallest bridge in California was constructed for a project that was eventually cancelled.

Bits and pieces from the ill-fated Donner Party's winter cabins.

One woman's Viking Castle on Lake Tahoe.

The location where the iconic movie character declared it was time to go home.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

This isolated outpost was once the only place to cross the Colorado River for hundreds of miles.

This unique art installation used boiler tubes from a decommissioned power plant to resemble Antelope Canyon.

Dramatic river bend surrounds a natural red-rocked pedestal.

These mid-century motels once housed the workers who built the Glen Canyon Dam.