A celebrity from the late Cretaceous period.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

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.

A computer bug so primitive it was an actual insect.

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

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

People escaping slavery may have hidden inside a corpse vault.

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

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

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

A nostalgic bibliographic gem.

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

The walls of the iconic dome are hollow and have a secret stairway.

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

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

A layered tribute to the work of mosaicist Isaiah Zagar.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.