An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

The innocent intentions of this monument are somewhat lost in the sculpture's muscled imagery.

The first memorial dedicated solely to the Black troops who fought for the Union.

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

A replica of the famous memorial statue at the Normandy American Cemetery hides in an office building in downtown D.C.

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

D.C. once had its own tiny rival to the New York Stock Exchange.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

The discovery site of the "Capitalsaurus," the official dinosaur of Washington, D.C.

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.

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

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

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

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

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

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

This unique historical monument features large concrete spheres designed to resemble fallen stars.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

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

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

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