The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

People escaping slavery may have hidden inside a corpse vault.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

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

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

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

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

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

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

The United States Capitol's former columns still stand.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

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

This unique historical monument features large concrete spheres designed to resemble fallen stars.

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

The national park was once a plantation estate.

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

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

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.

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

The oldest continuously operating fish market in the United States.