Located more than 600 feet beneath sea level, this tunnel boasts the world's first undersea roundabout.

This icon of the Atomic Age now lays dormant.

Florence’s mother built a stairway down to her daughter’s coffin so she could comfort her during storms.

Train cars and railroad artifacts abound at this restaurant devoted to railway history.

This decommissioned nuclear power plant offers tours of its Communist-era control room and reactor hall.

The site of the gruesome massacre—and maybe cannibalism—of five men, a tragedy that made Alferd Packer infamous.

Natural time capsule containing an alien ecosystem.

This is what trains will look like after the zombie apocalypse.

One of Frank Lloyd Wright's greatest—and favorite—architectural masterpieces was almost lost.

Six tiny houses built for working class people form the largest intentional cluster of Wright homes anywhere.

This public space is speckled with the eerie remnants of a defunct amusement park.

This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.

18th century anatomical amphitheater of the Royal College of Surgery of Barcelona.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

The world's largest squirrel statue clutches a pecan bigger than your head.

On the outskirts of a desert trading village high on the Andean plain, steel giants have been destroyed by salt winds.

At night, bats patrol this magnificent 18th-century space in search of book-eating pests.

The majority of the museum's large collection is held in a storage space open to the public a few times a year.

The stone circle honors the 19 firemen who perished during the Yarnell Hill Fire.

The famed architect designed this Minnesota gas station of the future with a lookout tower.

This unique crypt designed by Frank Lloyd Wright for his longtime friend was not completed in either man's lifetime.

This futuristically sylvan church is a glass-enclosed marvel of modern architecture.

A metal ring in the middle of the road marks the exact spot where the Soviet satellite crash-landed in 1962.