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

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

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

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

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

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

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

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

The national park was once a plantation estate.

Art deco landmark on the outskirts of Washington, D.C.

Decades before the scandal, this staircase on the river was a literal "water gate."

The most accurate timepiece in the world.

The oldest continuously operating fish market in the United States.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

The "lovely red Vega" of the legendary record-settling pilot.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Largest Roman Catholic church in North America.

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

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

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

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