A former major munitions plant that has been converted into a sprawling art space.

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

The United States Capitol's former columns still stand.

A haunting tribute to pioneering photographer Clover Adams.

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

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

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

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

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

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

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

A much-maligned monument to teetotalism.

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

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

Home to items never before seen by the public.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

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

Current docking place of the SS United States, the fastest transatlantic ocean liner.

A museum dedicated to the strange and extravagant costumes and memorabilia of the mummers, a tradition older than Philadelphia itself.

This elaborate towering structure was once famed for its revolutionary height.