Many generations of travelers have passed through the steep, smooth walls of this canyon.

Besieged by war, this castle ruin has crumbled into a peaceful picnic spot.

The ruins of a 12th-century Cistercian monastery can be found alongside World War II tank traps and pillboxes.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

A fire lookout atop a glacial pinnacle is reached by climbing three vertiginous flights of stairs.

This corn maze so big you may want to pack a lunch, and possibly a flaregun.

The final remnant of the Arkansas zinc industry is this historically protected ghost town.

Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

You'll need cowboy boots to trek to this old-fashioned saloon nestled in a giant natural cave.

A rusted metal giant pays tribute to Birmingham’s industrial past.

These ruins are all that's left of the former Alabama State Capitol.

This ghost town houses the remains of Alabama's old state capital.

The remains of a foundry and old blast furnaces destroyed during the Civil War are preserved in this central Alabama park.

The remains of an idyllic small town built for the film 'Big Fish' still stand around a rundown main street.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

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

A tiny village is home to the world's only diner completely devoted to the many varieties of traditional Swedish dumplings.

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

A thin pane of glass keeps visitors from sliding off this futuristic skywalk.

Stay overnight in the world's most sleekly designed rabbit hole, free of charge.

For six months of the year, three giant mirrors direct a pool of sunshine onto this otherwise occluded town.