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

This splendid Versailles-inspired mansion has the largest French-style formal gardens in North America.

The home and studio of a visionary woodworker now stands as a museum and example of his artistic genius.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

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

An astounding collection of medical specimens, including bits of President Lincoln.

A benevolent, 16-foot-tall river dragon lives on a suburban lawn.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The shelves in the back of this thrift store are devoted to saving, not selling, retro tech.

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

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

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A derelict bit of transportation infrastructure hidden in the woods.

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.

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

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

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

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

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

The United States Capitol's former columns still stand.

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

Turntable anonymously received orphans, alms, and groceries.

Herbert Hoover's "Brown House" rural presidential retreat was a PR disaster amid the start of the Great Depression.