It houses the remains of a 17th-century version of the Titanic.

Micro-nation based around a nine-story high illegally built tower.

The world's largest model of our planetary system.

The world's first ice hotel is still one of the most elaborate and beautiful.

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

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

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

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

Stone carvings record the Norse myth of Sigurd, providing a glimpse into Scandinavia's transition from paganism to Christianity.

A poignant memorial to a young boy whose death spurred a dramatic increase in organ donations in Italy—dubbed the "Nicholas Effect."

A stealthy Apache hideaway that became the haunting site of a mass grave.

The largest wooden building in the world now houses a fascinating collection of aircraft.

Only known mainland rookery of the threatened Stellar sea lion.

Water of undetermined depth has attracted rare fish and cult leaders alike.

Where the polar bear watches over everything, and every drink is a double.

The longest continuous lava tube in Oregon.

Massive crater in central Oregon.

Behind this beachfront shop lies a spectacular, colorful sea cave with an equally colorful past.

One of the most remote spots in America and the first protected wilderness area in Nevada, named after an old legend.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

Secret US military film studio in the Hollywood Hills.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

The beauty and the beast of hydraulic mining is on full display at this California Historic State Park.