A line of blue paint marks the route of the inaugural parade.

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

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

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

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

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

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

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

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

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

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

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

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

Before Nixon, "watergate" meant canals.

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

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.”

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

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

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Go take a picture with the inventor of the daguerreotype photographic process.