The last remaining location of a drive-up hot dog stand named after a local pool shark.

Built to defend Washington D.C. during the Civil War, this fort became a post-war nucleus for a thriving Black community.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The national park was once a plantation estate.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

The most magical part of this Latin American and Caribbean art museum is a room covered in beautiful blue tiles from floor to ceiling.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

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

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

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

America's first federal monument.

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

Long buried under the 20th-century landscape, this lift lock of the Alexandria Canal is the lone remnant of an ambitious early American transportation project.

The narrowest house in America is seven feet of pure spite.

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

A superbly preserved example of Georgian residential architecture that was once home to one of the founders of Alexandria, Virginia.

A massive, majestic mammal watches over pedestrians from his perch atop a former B.P.O.E. lodge.

An original apothecary from 1792.

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

Life in this isolated, hilltop lighthouse was lonely, but it sure was lovely.

This old-world mansion with lush gardens is a gem in the heart of Silicon Valley.

A sparse, solitary sequoia still stands as a living tribute to the famous conservationist who planted it—but it's dying.