Take a step into the workshop where Edison and his employees revolutionized the world.

A wondrous old library overlooking the nation's capital.

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

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

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

A much-maligned monument to teetotalism.

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

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

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

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

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

D.C. once had its own tiny rival to the New York Stock Exchange.

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

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

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

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

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

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

One of only two remaining Victorian-era greenhouses in New York.