Go take a picture with the inventor of the daguerreotype photographic process.

The national park was once a plantation estate.

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

A much-maligned monument to teetotalism.

Art deco landmark on the outskirts of Washington, D.C.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

It was once the base for a series of domestic terror attacks.

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

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

The "lovely red Vega" of the legendary record-settling pilot.

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

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.

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

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

A super-sized promotional trick that is now a D.C. landmark.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

Largest Roman Catholic church in North America.

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

The most decorated dog of World War I is preserved in the Smithsonian.

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

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

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

This grand gothic brewery has been pumping out suds for over a hundred years.