A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

Outsider art meets paleontology at this roadside reptile repository.

Rumor has it the hot dog stand was targeted by two Russian nuclear missiles.

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.

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

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.

A small and somewhat hidden memorial to 68 local veterans of the Vietnam War.

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

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

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

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

An original apothecary from 1792.

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.

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.

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

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

Artifacts of whaling, with both its perils and adventure, are housed in this museum in a former candle factory.

This city park was once a lookout point for George Washington’s army during the Battle of Brooklyn in 1776.

You can still ride this 100-year-old work of art in Brooklyn's largest public park.

The failure of one component toppled this entire bridge during rush hour.