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

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

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

A nostalgic bibliographic gem.

The oldest continuously operating fish market in the United States.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

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

People escaping slavery may have hidden inside a corpse vault.

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

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

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

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

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

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

A wondrous old library overlooking the nation's capital.

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

Once the center of a thriving early Black community called Martinsburg.

The only public school for Black children in the region from 1895-1936.

The hidden ruins of a mill that is linked to an attempt to assassinate the vice president of the United States.

Built in 1815, the stabilized ruins of the grist mill and sawmill are now gated, but interpretive displays on the features and functions of the mill preserve its history.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

This statue of the "father of television" stands prominently in the United States Capitol.