A small museum along the Susquehanna River is home to a rich collection of Native American artifacts.

This elaborate towering structure was once famed for its revolutionary height.

The oldest farmer's market in America is so ancient it was approved by the King of England.

Although built to generate electricity for Marylanders, this dam has become an all-you-can-eat buffet for American bald eagles.

This historic lighthouse was well known for the large number of women who served as its keeper.

A rural colonial settlement that contains the remains of a store and cooper.

The oldest surviving botanic garden in the United States.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

A daily replay of the experiment that proved the rotation of the Earth.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

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

While not recognized by Guinness, this chocolate waterfall is likely to be the world's largest.

The ruins of a town wiped out by the second-largest earthquake in recorded history.

FDR hoped to find a cure for polio in this Georgia town's warm springs.

This haunting tombstone comes complete with a heartbreaking story of love and loss.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

A bizarre roadside attraction and the first instance of miniature golf in the world.

Yo, Adrian!

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

The land is home to swimming ponies and a legendary 18th-century treasure.

The Decoy Capital of the World.

Eccentric concrete mansion and museum designed and built by hand from the inside out.