The 28,000-year-old specimen is remarkably intact.

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

A surprising, but overlooked example of geology in the middle of the nation’s capital.

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

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

The discovery site of the "Capitalsaurus," the official dinosaur of Washington, D.C.

The institution is sitting on a goldmine of 21,000 paints, varnishes, pigments, and primers preserved for posterity.

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

A clone of a cloned tree that was so important it allegedly had its own guards.

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

Decades before the scandal, this staircase on the river was a literal "water gate."

A celebrity from the late Cretaceous period.

A computer bug so primitive it was an actual insect.

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

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

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

An Industrial Revolution-era public work that purified water using nothing but sand.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

People escaping slavery may have hidden inside a corpse vault.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

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

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

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

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