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

A surprising, but overlooked example of geology in the middle of the nation’s capital.

This unassuming passageway played a key role in one of the most important events in U.S. history.

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

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

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

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

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

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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

This restaurant has been a haven for D.C.'s LGBTQ community since the 1950s.

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

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

A portal into the bricked up canal that runs through the heart of Washington D.C.

These abandoned waterworks are crumbling into the Potomac River.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

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

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

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

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

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

Look closely and you’ll notice that the color changes a third of the way up the tower.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.