One of Monterrey's oldest buildings is perched atop a hill boasting impressive views of the city.

Inside this mountain lies several kilometers of breathtaking caves.

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

Tucked behind New Jersey's abandoned Gingerbread Castle lie the eerie ruins of a once-flourishing paper mill.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

A hidden alley in urban Baltimore is a haven for graffiti artists.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

An abandoned asylum where patients have been forgotten but their possessions remain.

An iconic steel and chrome diner from the 1940s left empty for nearly 20 years is in danger of being demolished.

An abandoned asylum once on the cutting edge of lobotomies may be reborn as a Christian college.

This decrepit abandoned building is made all the more eerie by its dark history.

The sprawling, eccentric estate of Ames and Ames, a brilliant botanist, and a genius inventor and artist.

This abandoned radar station from the Cold War era now only broadcasts a seriously ominous air of isolation.

Empty since 1989, now falling into ruin.

A small Richmond island dotted with the remnants of hundreds of years of history.

A deteriorating 1990s Girl Scout camp in a beautiful lush park on Lake Ontario.

This once luxurious Catskills resort is now a haunting ruin.

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

An abandoned dollhouse factory.

This abandoned Poconos resort is haunted by a history of kitschy romance and a violent fugitive.

World War II bunker still standing on the New Jersey beach.

This historic iron-working village is now a ghost town so immaculate that it looks as though it was recently built.

Vacant Beaux-Arts buildings that serve as reminders of a beach town’s glory days.

This tiny New Jersey village has lived many lives but seems determined to remain a ghost town.