This large garden vase urn has nothing to do with the seventh U.S. President—it was designed by one landscape designer to honor another landscape designer's contributions to the National Mall.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

The only female equestrian statue in Washington, D.C. is a 15th-century French heroine.

After James Madison's death, his wife and former First Lady Dolley Madison lived in this yellow building near the White House.

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

A glimpse of the Pacific Northwest‘s indigenous culture in Washington, D.C.

The Conduit Road Schoolhouse is one of the last one-room schoolhouses remaining in Washington, D.C.

The span is crooked and made from two older recycled bridges.

These abandoned waterworks are crumbling into the Potomac River.

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

People escaping slavery may have hidden inside a corpse vault.

This small hilltop church weaves the urban history of Washington, D.C. with the national history of the United States.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

Depending on who you ask, this controversial treehouse is either a charmingly creative child's playhouse or an illegal encroachment on public land.

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

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

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

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

One of the last mosaic tile facades found in the city.

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

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

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

Surrounded by a verdant garden and a backdrop of ivy, a monument to beloved poet Khalil Gibran stands outside of the Lebanese embassy.