A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A derelict bit of transportation infrastructure hidden in the woods.

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

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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

A painfully obvious spy house sits right across the street from the Russian Embassy.

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

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

A historic neighborhood church is reborn as a psychedelic arts collective.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

This grand gothic brewery has been pumping out suds for over a hundred years.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Home to items never before seen by the public.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

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

Atop this media building, two hives containing more than 30,000 bees keep the surrounding area vibrant.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

A public art jibe at one of the United States’ oldest and longest-serving senators.

The district's only illusionarium supports free writing programs for local students with every purchase.

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

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

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