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

The oldest continuously operating fish market in the United States.

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

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

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

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

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

The most accurate timepiece in the world.

There’s a hidden military meme engraved on the World War II Memorial.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

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

Exact replica of the ancient monument, but much, much lighter.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

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

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

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

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

The national park was once a plantation estate.

The romance of early commercial flight still fills this Art Deco destination.

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

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

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