The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

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.

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

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

Spectacular mineral formations fill these caves, which have been used for everything from smoking meat to stashing illicit liquor.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

One of Belgrade's most beloved animals.

America's first federal monument.

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

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

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