Disks are rolled out onto the south lawn to absorb the impact of Marine One's wheels like giant coffee coasters.

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

A portal into the bricked up canal that runs through the heart of Washington D.C.

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

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.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

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

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

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

Before Nixon, "watergate" meant canals.

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

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

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

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

Decades before the scandal, this staircase on the river was a literal "water gate."

The national park was once a plantation estate.

There’s a hidden military meme engraved on the World War II Memorial.

This magnificently macabre shield shows the power of chivalrous love in medieval times.

The medieval woodcut-style artwork chronicles life in medieval London.

This innovative steam machine was no doubt the most famous of the pioneer locomotives.

An architectural oddity hides in plain sight on this iconic London bridge.