The world’s first penitentiary, meant to be humane, drove men insane.

Here, at the “world’s longest art gallery,” you’ll find forty miles of ancient petroglyphs and pictographs.

Pennsylvania's highest point is spotted with boulders which were pushed to the surface by nothing but cold.

Near-constant high winds deform the trees on Spruce Knob, the highest point in West Virginia.

The highest point in Washington state is a volcano covered in glaciers.

Despite a legend that says this highest peak in Oregon was climbed in high heels, scores of people have died on its slopes.

The highest point in the state of New Hampshire, and while unlikely "the worst weather in the world," it sure seems that way to hikers.

The highest point in North Carolina and the United States east of the Mississippi River, Mount Mitchell is named after argumentative explorer Elisha Mitchell.

The highest point in Maine is a grand gift to the state citizens that also happens to be one end of the Appalachian Trail.

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

This poor little statue is the most vandalized memorial in Washington.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

The walls of the iconic dome are hollow and have a secret stairway.

Every drop of D.C. tap water flows through this old waterworks.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

A perfect circle of 24 mysterious holes dates back to prehistoric times.

An indoor miniature village and labor of love for Laurence Geiringer, a model railroad enthusiast.

A failed piece of Orientalism has become the proud symbol of a community.

In which a local geological marvel becomes a quaint roadside attraction.

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