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

A short hike into the mountainside forest reveals a decaying 1890s town.

Street artists transformed this abandoned industrial neighborhood into one of Europe's largest graffiti exhibitions.

The world's oldest individual clonal tree looks like a wimp despite standing tall for 9,550 years.

Crooked windswept pines give this old forest an enchanted and magical look.

Bring your hiking shoes, wool socks, and thermal underwear for a stay in these cozy forest huts.

A series of modernist treehouse hotel rooms grace the outskirts of an Arctic forest.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

Unknown to many, this sparkling turquoise lake hides amid Oregon's snowcapped mountains.

This frequently-photographed waterfall takes only a short hike to visit.

This great stone guardian of the forest is a relic from the land's volatile volcanic past.

This extinct shield volcano is the lightning rod of the Cascades.

The second largest waterfall by volume in the U.S., Willamette Falls is outdone only by Niagara in the amount of water that is pushed northward.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This massive library holds what was once the largest book collection in the world.

French scientists make up the majority of the few humans to occupy this remote island in the extreme southern Indian Ocean.

A naturally beautiful, seemingly bottomless deep blue spring.

This abandoned Slovenian military barracks has become a punky-political art squat.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

This massive subterranean fissure is known as the "underground Grand Canyon."

A unique hotel for the artistic soul.