The national park was once a plantation estate.

There’s a hidden military meme engraved on the World War II Memorial.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

This nine-story building is the oldest standing skyscraper in D.C.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

A derelict bit of transportation infrastructure hidden in the woods.

Color-coded signs direct drivers on a network of routes designed to avoid Pittsburgh traffic.

It was once the base for a series of domestic terror attacks.

FDR's Art Deco hospital tower was hopelessly inefficient.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

This unique historical monument features large concrete spheres designed to resemble fallen stars.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

The tunnel under the Capitol Building where Congress takes out its trash.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

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.

One of the best places to see feral Colonial Spanish Mustangs in the United States.

A historic custom house with ties to George Washington is now a shrine to local nautical history.

The whole world in one water tank.

One of the oldest anatomical theaters in the U.S. still in use was once the site of an infamous cadaver riot.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

This simple convenience store sits on the location where the Ouija board was named—and has a plaque to prove it.

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.