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

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

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

The site of the climactic scene from the classic horror film is now a historic landmark.

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

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

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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.

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

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

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

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

A nostalgic bibliographic gem.

The privately owned cemetery that holds room for Washington's finest when they step down from life.

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

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

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

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

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

The walls of the iconic dome are hollow and have a secret stairway.

Home to a vast and influential collection of Shakespeareana.