When an ancient supervolcano erupted, some of Nebraska's prehistoric animals were forever preserved in ash.

This erect, phallic geological spire wasn't always named so domestically.

An experimental, automotive replica of Stonehenge.

Mark Twain once stopped at this rest station during his journey to Nevada.

This shallow pit was once used to send over 20,000 buffalo plummeting to their death.

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.

Surrounded by a hundred mile radius of billboards, Little America is a roadside attraction whose primary appeal is hospitality.

A popular rock that acted as a waymarker for American pioneers.

This prison-turned-museum is a remnant of the Old West's grizzly, violent past.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The first declared National Monument in the United States.

This advertisement for talcum powder was painted on the rock face and has since defied removal.

One of the only memorials dedicated to journalists who died in combat.

The whole world in one water tank.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

Built by the patriotic residents of Boonsboro in a single day.

A Civil War Museum with some notable medical antiques.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

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

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

Bizarre Cavern.

An astounding collection of medical specimens, including bits of President Lincoln.

An eerie, decaying ghost town destined to fade into the forest.