This homestead was occupied by Union soldiers, who believed the owners were signaling Confederate forces.

A super-sized promotional trick that is now a D.C. landmark.

A historic cemetery filled with quirky faux wood art and unique tombstones.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

People escaping slavery may have hidden inside a corpse vault.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

This pharmacist and his patient greet visitors to the National Community Pharmacists Association.

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

Originally dubbed "Retirement" by the Navy Commodore who built it in 1780, this beautiful mansion is now the centerpiece of a suburban community park.

Dedicated to a U.S. Army lieutenant colonel who was also a bird watcher and artist.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

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

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

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

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

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.

These light, hollow rolls have been linked to Acadia National Park since the 1890s.

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

A gift from Japan, 17th-century lantern stands among the cherry trees at D.C.'s Tidal Basin.

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