A well-worn trail through thick woods in northern Montgomery County leads to an old schoolhouse.

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The former home of elite checkers battles of the Capital Pool Checkers Club.

This abandoned sea fort has become an accidental bird sanctuary.

The slate extracted from these Pennsylvania quarries was once hailed as the finest in the world.

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

Exact replica of the ancient monument, but much, much lighter.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

The first national memorial to honor all women suffragists stands on land where suffragists were once imprisoned.

The final residence of an educator, civil rights leader, and presidential advisor was also the first headquarters of the National Council of Negro Women.

Endless rows of boxes of paper records line the hallways of the archaic federal facility where guns are traced.

A giant time capsule not scheduled to be cored until 2040.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

Unannounced visitors are now welcome at the site of the largest Prohibition-era bootlegging operation in the region.

Bizarre Cavern.

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

A line of blue paint marks the route of the inaugural parade.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

This abandoned church languishing for decades is now one man's passion project and subject of paranormal investigators.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

At Brandy Station, Civil War soldiers left their mark on the battlefield and the walls of this small wooden house.

A bunker "with enough U.S. currency to replenish the cash supply east of the Mississippi" in the event of nuclear war now protects nitrate film.