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

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

Washington's iconic carousel has a nice piece of Civil Rights history.

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

Go take a picture with the inventor of the daguerreotype photographic process.

Art deco landmark on the outskirts of Washington, D.C.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

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

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

The house where John Wilkes Booth conspired with his co-conspirators.

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

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

People escaping slavery may have hidden inside a corpse vault.

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

A derelict bit of transportation infrastructure hidden in the woods.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

A nostalgic bibliographic gem.

A wondrous old library overlooking the nation's capital.

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

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

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

This grand gothic brewery has been pumping out suds for over a hundred years.

Home to items never before seen by the public.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.