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

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

More than 500 unique and specially designed cases collected by D.C.'s "Harmonica Case Man."

A public art jibe at one of the United States’ oldest and longest-serving senators.

Atop this media building, two hives containing more than 30,000 bees keep the surrounding area vibrant.

Garments from across the globe call this hidden gem home.

Home to two notable early-20th-century Black educators, Lucy Slowe and Mary Burrill.

One of the first Second Empire-style buildings constructed in North America.

The former home of Lillian Evans Tibbs and her grandson, Thurlow Evans Tibbs Jr., whose prodigious contributions to music and art spanned more than 90 years.

The last remaining building in Washington, D.C., built by H.H. Richardson, one of America's most iconic architects.

A street in front of NASA's D.C. headquarters has been named in honor of the Black women who were essential to early spaceflight.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

It was once the base for a series of domestic terror attacks.

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

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

The largest clock face in the United States is twice the size of Big Ben and infinitely more ad-sponsored.

A take-out restaurant that only serves cuisine from countries with which the United States is in conflict.

The last funhouse of its kind, where guests enter through the mouth of an 80-year-old blue whale.

Color-coded signs direct drivers on a network of routes designed to avoid Pittsburgh traffic.