The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

An emerald-green grotto just a short trip from Austin.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

A crumbling hospital from the 1850s on Roosevelt Island.

On the Oregon coast there is a natural hole that seems to be draining the sea.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

World's first "penitentiary," meant to be humane, drove men insane.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

World's largest collection of serial killer artwork and other macabre exhibits.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

Non-profit time travel mart sells goods you would need for a trip through the fourth dimension.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This road in the Great Smoky Mountains was supposed to assuage a displaced community, but ended up a $52 million dead end.

The remains of the iconic train crash from the movie The Fugitive can still be found rusting along the Great Smoky Railroad.

Mysterious ancient boulder carved with petroglyphs in the mountains of Western North Carolina.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

A quintet of history museums make this Virginia graveyard as much a resting place for funereal history as it is for people.

A "hospital" where people went to be quarantined, die, and be buried in the yard.