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.

One of the best-selling bar bands in American music history is commemorated in their hometown's Five Points neighborhood.

A handful of beehive kilns are all that’s left of a historic brick-making empire.

This Delaware River bridge is emblazoned with a catty slogan from a more prosperous time.

This small pedestal marks the spot of the first lot of land sold in Alexandria, Virginia in 1749.

Once the largest trading firm of enslaved people in the U.S., this building is now a museum that preserves Alexandria's dark past.

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

This sprawling farm was once a Cold War-era hideaway for the nation's top diplomats.

This historic boathouse was constructed using salvaged lumber from burned barns.

Garments from across the globe call this hidden gem home.

The stone marker that Mason and Dixon placed at the eastern end of the famous north-south border they surveyed.

An isolated island home to one of the oldest English-speaking communities in the region and Maryland's state dessert.

The only labyrinth within the city of Alexandria.

Beneath unsuspecting visitors feet, a capsule containing pieces of America’s civil rights history.

Go take a picture with the inventor of the daguerreotype photographic process.

This site is believed to be connected to the oldest house in Arlington County.

The narrowest street in Paris.

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

The only Leonardo Da Vinci painting in the Western Hemisphere.

The 28,000-year-old specimen is remarkably intact.

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

This little-known relic crypt holds stolen parts of a Roman Empress.

The history of radiation is on safe display at the foot of a radiation science laboratory.

Site of a classic 19th-century physics experiment to prove the earth is rotating.