Once a sewer culvert, this road tunnel now offers cyclists and pedestrians a subterranean stroll under the C&O Canal.

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

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

People escaping slavery may have hidden inside a corpse vault.

The oldest house in Washington, D.C. wasn't originally constructed in the nation's capital.

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

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

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

A tribute to the pop culture icon overlooks this Washington D.C. intersection.

A surprising, but overlooked example of geology in the middle of the nation’s capital.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.