A museum dedicated to exhibiting remarkable outsider art.

Home to items never before seen by the public.

The oldest continuously operating fish market in the United States.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

Look closely and you’ll notice that the color changes a third of the way up the tower.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

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

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

The most accurate timepiece in the world.

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

A tiny piece of the Moon is embedded in this stained glass masterpiece.

Rumor has it the hot dog stand was targeted by two Russian nuclear missiles.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The national park was once a plantation estate.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The site of the climactic scene from the classic horror film is now a historic landmark.

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.