The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

Revel in the Victorian splendor of the world's oldest eating establishment inside a museum.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

A priceless collection of the Nation's cryptologic history.

Its diverse collection of computers and technology spans the ages.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

Home to items never before seen by the public.

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

The tunnel under the Capitol Building where Congress takes out its trash.

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

A celebrity from the late Cretaceous period.

Look closely and you’ll notice that the color changes a third of the way up the tower.

Perhaps the most scandalous statue of America's first president.

After the attack on Pearl Harbor, rocks and fossils from every U.S. state were collected into a pyramid of national unity.

255 feet of suds, scrubbers, and blow dryers.

A 24-hour vending machine restocked daily with homemade full-sized pecan pies.

The world's largest squirrel statue clutches a pecan bigger than your head.

A grove of colossal man-made flowers built to collect the sun's rays.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

This Boeing KC-97 tanker is now a restaurant for aviation lovers.

This Art Deco fortress in upstate New York gives Manhattan's vaunted examples of the style a run for their money.