Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

An overlooked memorial honoring the local Washington residents who died in World War I.

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

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

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

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.

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

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.

A nostalgic bibliographic gem.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

The site where Poe "in great distress, and ... in need of immediate assistance" likely died.

A 200-year-old bar with a cheeky name claims to have served Edgar Allan Poe his final drink.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

The trials and tribulations of marking Poe's grave.

This elaborate towering structure was once famed for its revolutionary height.

The story behind the mysterious symbol painted in front of the historic university's famous Rotunda.

FDR's Art Deco hospital tower was hopelessly inefficient.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

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

Largest Roman Catholic church in North America.

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

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