An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

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

The most decorated dog of World War I is preserved in the Smithsonian.

A nostalgic bibliographic gem.

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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

Home to items never before seen by the public.

FDR's Art Deco hospital tower was hopelessly inefficient.

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

The Decoy Capital of the World.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

Fiji mermaids, mummified remains, and recreated cryptids are among the morbid oddities at this Maryland museum.

Once America's tallest structure, now a Baltimore landmark.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones' Locker.

The land is home to swimming ponies and a legendary 18th-century treasure.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

The Pentagon sits on a former island that was in Virginia at low tide and D.C. at high tide.

The rogue roots are gradually consuming some of the historic marble grave markers.

The naval commander’s proudest moment in battle is memorialized in this unique tomb at Arlington Cemetery.

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.