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

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

An original apothecary from 1792.

This cannon dating to 1755 has stood guard at this suburban intersection since 1915.

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

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

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The site of the climactic scene from the classic horror film is now a historic landmark.

The oldest continuously operating fish market in the United States.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

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

The national park was once a plantation estate.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

This fertility idol of questionable authenticity inspired an iconic Indiana Jones artifact.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

Where royalty waits in the height of luxury.

Amsterdam's narrowest house facade is a monument to 17th-century tax evasion.

Some 80,000 Delft Blue tiles line the inside of this Amsterdam walkway.

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

A trio of red, white, and blue stones embedded in the streets of Leiden are markers of medieval territory and law.

The attic of a four-century-old canal house hides a clandestine church.