This magnificent stepwell is designed as an inverted temple and adorned with 1,500 sculptures.

One of the oldest living oak trees in the Southeast.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

A part of the world's largest marsh seems to be growing bright red Martian grass.

The 5,000-year-old megalith is believed to be Scotland's tallest standing stone.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Hidden in the hills is a mysterious stone structure, known only to a few.

This abandoned amusement park was built on a site with a dark history.

A well-preserved Ancestral Puebloan ruin tucked beneath a desert cliff.

A crumbling hospital from the 1850s on Roosevelt Island.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

A Beaux-Arts triumph set to become Ford's innovation campus

The former locus of Boston's high culture has been shuttered and buried for over 70 years.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

This remote island in Iowa was abandoned after being devastated by flood.

See just what life was like in a 19th-century prospecting town.

This former luxury resort in Kaua'i is now an abandoned relic.

Abandoned silver mine strewn with wrecked and twisted structures.

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

Started as a kitchen garden, now the second largest botanical garden in the world.

This modern monument to pagan belief looks like it was transported straight from ancient times.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

Less a museum than a bizarre fantasy world created by artists and engineers.