An astounding collection of medical specimens, including bits of President Lincoln.

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

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

Every drop of D.C. tap water flows through this old waterworks.

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

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

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

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

Home to items never before seen by the public.

The house where John Wilkes Booth conspired with his co-conspirators.

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

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

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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

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

At 207 feet, one of the world's longest continuous escalators.

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

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

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

The most accurate timepiece in the world.