The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A much-maligned monument to teetotalism.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

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

The fountains of the U.S. Navy Memorial are annually salted with water from the Seven Seas as part of a nautical ritual.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

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

Where the U.S. government kept its actual treasure, before Fort Knox.

A brass plaque dedicated to a convicted cannibal hangs in the National Press Club, and that's not even the craziest part of the story.

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

Four bald cypress trees in Lafayette Square, across from the White House, mark the southern edge of a 100,000 year old cypress swamp.

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

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

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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

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

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

These recently uncovered walls are all that's left of Washington, D.C's first defense contractor.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

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

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.