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

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

Home to a vast and influential collection of Shakespeareana.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

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

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Home to items never before seen by the public.

One Confederate statue that accurately reflects the ugliness of its subject.

A swamp that was the site of prehistoric water burials also managed to preserve its corpses for millennia.

A building so large that it has its own weather.

An octet of classic chrome trailers speared into the ground act as a tribute to the silver bullets of the open road.