This long, dark tunnel is open to hikers, but those without lights are known to get confused even on the straight path.

A whimsical village of unique treehouses resides in a Washington forest.

An abandoned 19th-century hospital now swirling in ghost stories.

A nearly abandoned 19th-century town on the Palouse.

The site of the Wellington avalanche, one of the America's worst railroad disasters.

Hundreds of hopeful gold miners came here to get rich, but only two years later the small town was deserted.

The century-old remains of an abandoned farm town in eastern Washington.

An obscure waterfall that looks like something out of a fantasy novel.

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

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

The second tallest railway trestle bridge in America.

This large Sitka spruce that appears to be floating in mid-air, has defied logic for years.

A surreal landscape where fanged rocks rise from the ground and the ocean feels like a great mystery.

Shoreline strewn with the remains of ghostly fallen trees.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

Stroll through a wonderland of stupendous moss-covered trees.

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

Once America’s most beautiful army base, this abandoned military fort on the coast of Monterey Bay has been left to the elements.

This family mausoleum is steeped in symbolism and looks more like a fantasy location than a grave.

This dilapidated ship carcass covered in trees is a striking sight.

This 50-ton ship on Orcas Island has never seen the ocean.

Four abandoned towers hidden above the Douglas fir forest in Washington.

This painted blacktop brings the classic arcade game to life.

A huge musical sculpture and other art installations on the National Oceanic and Atmospheric Administration grounds.