A physical reminder of Earth's ancient past, this rock results from the photosynthetic processes of some of the oldest forms of life.

Everyone's invited to put on a miniature concert with this world-class musical wonder.

Since 1947, this living history museum has been providing an immersive look at life in Plymouth Colony.

Proto-CIA agents trained with grenades in the sand traps and fired machine guns from the fairways.

An allegorical sculpture in Maryland wears the artist’s politics on its trunk.

Tiny observatory made big contributions to the study of the Earth's motion.

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

This suburban house is made of dirt, and almost sparked a revolution in home construction.

The development and impact of electronic media showcased in a picturesque farmhouse in Maryland.

This one-room cabin where the young colonel slept during the French and Indian War.

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

The ruins of this long-abandoned unsuccessful gold mine can still be found.

Three abandoned missile silos are hiding in plain sight behind a suburban development in Maryland.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

The wooded estate of the Forest Service employee responsible for D.C.’s cherry blossom trees.

FDR's Art Deco hospital tower was hopelessly inefficient.

The whole world in one water tank.

This abandoned Victorian-style house was built in 1884.

Time travel with sweets across history at this research-based candy store.

This four-story steel sphere in Maryland was used to test biological weapons.

A Civil War Museum with some notable medical antiques.

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

This Maryland farm is known for its amazing corn mazes and its 30-foot junkbots.

In this cemetery stands the country's first public crematorium.