The all-but-forgotten cemetery is Eastern Loudon County's largest African-American burial ground.

The Aldie Gristmill was once the largest factory of its kind in Loudoun County.

The last of Fairfax County's one-room schoolhouses.

This hidden treasure provides a charming access point along the south side of Baker Park.

According to local history, this cast-iron canine was nearly melted down for bullets during the Civil War.

Historic barracks utilized during both the Revolutionary War and the Civil War.

Rumors persist that a bottle of whiskey is sealed within this Demijohn-shaped adornment.

One of the last schoolhouses constructed in the early 20th-century still standing in Montgomery County.

This suburban park recalls the history of a famous tavern. Despite the name, it's no ordinary place!

The whole world in one water tank.

This propitious plastic porcine has been petitioning park visitors to pick up after themselves for more than 50 years.

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

One of the oldest standing structures in Montgomery County, Maryland.

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

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.

This massive swimming pool is the high tech home to the human-powered submarine races.

Public works and national defense project meant to carve a canal all the way across the state of Florida.

Visitors flock to see this church tower's unintended feature: It happens to resemble a giant chicken from multiple points of view.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Decades before the scandal, this staircase on the river was a literal "water gate."