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

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

This grand gothic brewery has been pumping out suds for over a hundred years.

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

The most accurate timepiece in the world.

A double agent hid information for the Soviet Union beneath this bridge for more than 20 years.

Home to items never before seen by the public.

At 207 feet, one of the world's longest continuous escalators.