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

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

In the heart of Tirana, this underground nuclear bunker has been transformed into a museum.

These towering spires and glowing walls are carefully crafted from hundreds of thousands of icicles.

Multiple waterfalls and several historic CCC buildings anchor this state park in Oregon's Willamette Valley.

Rushing water plunges over a 100-foot drop created by an ancient lava flow at this majestic waterfall.

One of the most comprehensive collections of historic Native American culture in the country reframes artifacts as artwork.

Shakespeare has been brought to life in this open air theater for the better part of a century.

The wooden airship was the largest flying boat ever built.

Home of Howard Hughes' Spruce Goose.

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

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

This massive mushroom has spent centuries eating its way across a huge swath of Oregon.

This nature center has one of the largest collections of native raptors in the Pacific Northwest.

This gorgeous beach hides behind two headlands in Oregon's Ecola State Park.

Where Nor'easters go to die.

Bridges, terraces, and replicas of historic structures all built of rock and petrified wood by one man.

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

The trunks of 3,000 year-old trees lurk beneath the surface of this crystal clear lake in Oregon.

A collection of colorful dinosaurs hidden in an actual rainforest.

Nestled between a college and a golf course, the garden is home to more than 2,500 rhododendrons.

10,000 flowered plants bloom in the City of Roses.

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

The longest continuous lava tube in Oregon.