This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

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

An overlooked memorial honoring the local Washington residents who died in World War I.

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

The national park was once a plantation estate.

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

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

The romance of early commercial flight still fills this Art Deco destination.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

A former major munitions plant that has been converted into a sprawling art space.

Once forgotten and built over, this historic Black cemetery now houses a poignant memorial.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

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

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

Taste the white whiskey that the United States' first president once distilled and enjoyed.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

These unusual rooms on wheels are holdovers from the 1960s.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

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

She stares out across six lanes of traffic, clutching a musket and infant with determination.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.