A super-sized promotional trick that is now a D.C. landmark.

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.

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

An Industrial Revolution-era public work that purified water using nothing but sand.

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.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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

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.

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

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

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

Home to items never before seen by the public.

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

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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

The "lovely red Vega" of the legendary record-settling pilot.

The towering figures were created from the cemetery's fallen old-growth trees.

This poor little statue is the most vandalized memorial in Washington.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

The first memorial dedicated solely to the Black troops who fought for the Union.