A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

Through the decades, Black music stars have performed at this historic hub for music and the arts.

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

The first memorial dedicated solely to the Black troops who fought for the Union.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

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

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

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

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

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

The sculptor was instructed to add “stallion attributes” to the general's bronze mare.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

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

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

A line of blue paint marks the route of the inaugural parade.

Home to items never before seen by the public.

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

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

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.