Sloth rehabilitation center in the jungle of Costa Rica.

This wildlife refuge is home to more than 200 species of birds, as well as monkeys, lizards, and other wildlife.

The same water that fills a luxury resort’s pools feeds these free hot springs in the rainforest.

This futuristic airport terminal was abandoned for decades before reopening as a hotel—with a vintage plane of its own parked out back.

After Christopher Columbus died, his son built a fancy house to rule from.

The oldest colonial fortress in the Americas was once the home and later prison of Christopher Columbus.

Built in 1512, the oldest cathedral in the Americas.

At first glance, little checkered structures on the hillside look like they house the living, not the dead.

This slowly crumbling mansion was home to one of East Africa's richest and most powerful slave traders.

In Zanzibar, a historic 19th-century palace is a reminder of the world's shortest war.

A serpentine highway twists and turns over the treacherous Norwegian Sea.

A memorial to 350 people burned at the stake for witchcraft.

Walk behind a 50-meter-high waterfall.

A living museum working to keep the traditions of building and repairing handmade wooden boats, ropemaking, and blacksmithing alive.

Longest road tunnel in the world features an air treatment plant and the illusion of daylight.

The design of this beautifully crafted building was inspired by Norwegian glaciers.

Housing the famous Norwegian ice-defying 19th century polar exploration ship.

Across the Pacific in a raft, a museum dedicated to Thor Heyerdahl's now legendary expedition.

Home to three historic ships from the age of Vikings.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

A stunning architectural yet functional feat, towering over Oslo.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

The only surviving piece of Copenhagen's 16th-century defensive wall.

Copenhagen's celebrated theme park and gardens.