Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

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

The resting place of a Civil War celebrity's amputated limb.

An alternate history park where the Union Army loses the war... to dinosaurs.

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

Nine of the very few concrete ships ever made in the U.S. are beautifully decaying off a Virginia pier.

Paranormal investigators claim this abandoned asylum is the most haunted spot in the eastern U.S.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Heron, whitewater rapids, and urban industrialism all add to the beauty of this concrete nature walk.

A railroad tunnel that, upon its completion, was considered one of the engineering marvels of the modern world.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

People escaping slavery may have hidden inside a corpse vault.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

These figures float and flutter in this fountain crafted by famed Swedish sculptor Carl Milles.

Exact replica of the ancient monument, but much, much lighter.

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

This church in Pittsburgh is home to the largest collection of religious relics in North America.

A larger-than-life statue of America's favorite sundae marks the place it was invented.

This beloved Baltimore spot features caged dolls, a giant Pez collection, and many, many mannequins.

A museum dedicated to exhibiting remarkable outsider art.

America's first nuclear-powered merchant ship is now a time warp to the atomic age.

This abandoned Victorian-style house was built in 1884.