Amid the sprawling Defense Intelligence Agency Headquarters is one of Washington's least accessible museums.

Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

Where the U.S. government kept its actual treasure, before Fort Knox.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

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

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

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

Seemingly unremarkable items like empty sushi trays, chef hats, and freshness stickers are being preserved so future generations can look back on this beloved cultural import.

The institution is sitting on a goldmine of 21,000 paints, varnishes, pigments, and primers preserved for posterity.

The most accurate timepiece in the world.

Sit where JFK proposed to Jackie or where Nixon dined on meatloaf at this storied pub.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

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

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

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.

A nostalgic bibliographic gem.

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

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

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

A wondrous old library overlooking the nation's capital.