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

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

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

Atop this media building, two hives containing more than 30,000 bees keep the surrounding area vibrant.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

Giftshop catering to cryptozoologists and anyone with a sense of humor.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

It was once the base for a series of domestic terror attacks.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

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.