America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

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

An overlooked memorial honoring the local Washington residents who died in World War I.

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

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

This forgotten boat elevator was an engineering marvel in its heyday.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

A historic arena where the Beatles played their first concert in the U.S.

Washington's iconic carousel has a nice piece of Civil Rights history.

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

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

The oldest continuously operating fish market in the United States.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

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

Largest Roman Catholic church in North America.

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

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A historic neighborhood church is reborn as a psychedelic arts collective.

Home to items never before seen by the public.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

The United States Capitol's former columns still stand.