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

The tunnel under the Capitol Building where Congress takes out its trash.

The National Park Service’s best-kept secret with views that rival any in D.C.

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

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

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

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

"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!”

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

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

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

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

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

When it comes to handsignals (and colonialism) rock always beats scissors.

A historic arena where the Beatles played their first concert in the U.S.

A much-maligned monument to teetotalism.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

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

The national park was once a plantation estate.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

FDR's Art Deco hospital tower was hopelessly inefficient.

Although built to generate electricity for Marylanders, this dam has become an all-you-can-eat buffet for American bald eagles.

This advertisement for talcum powder was painted on the rock face and has since defied removal.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.