This huge pile of volcanic boulders hides a stunning network of secret grottoes.

Once in a state of dilapidation, this candy-inspired fortress is now being revived.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

One of the U.S. Forest Service's only mansions is outfitted with a dinner table for floating food.

This jail which was in service for over a century is now open for curious visitors.

This eerily well-preserved coal town was saved from destruction by a Sean Connery movie.

A field of nothing but boulders which resembles a giant's gravel driveway.

A hamlet full of permanent Christmas spirit holds one of the earliest theme parks in the United States.

The dairy farm in upstate New York where nearly half a million people gathered for three days of peace and music in 1969.

Oldest existing wire suspension bridge in the United States.

The home of the first American-born saint is one of the only curved buildings in New York.

The oldest continuously inhabited street in America.

This stone gatehouse was once the entrance to a historic mountain resort, and it had a cameo in a cheesy cult horror movie.

Dedicated to the art and science of glass in equal measure, this space is as much laboratory as museum.

A winding, cliffside stretch of road overlooking the Delaware River.

"A hideous albatross in the Hudson River Valley."

Why have you never heard of the second most popular tourist site in New York?

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

Avoid gangster interaction while window-shopping.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

This Niagara Falls tourist trap is a world bright with neon and curiosities that will inspire love, hate, or a mixture of both.

Local lore claims this park is named after a young woman who jumped off a cliff.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.