One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

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

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

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

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

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

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

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

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

The national park was once a plantation estate.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

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

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

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

A celebrity from the late Cretaceous period.

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

The oldest continuously operating fish market in the United States.

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

There's a crumbling old mansion inside the Smithsonian National Zoo.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

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

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

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

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.