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.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

A tiny piece of the Moon is embedded in this stained glass masterpiece.

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

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

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

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

Home to items never before seen by the public.

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

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

Washington's iconic carousel has a nice piece of Civil Rights history.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

An overlooked memorial honoring the local Washington residents who died in World War I.

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

Look closely and you’ll notice that the color changes a third of the way up the tower.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

An amazing example of early-20th-century architecture, this church features marble transported from Utah.

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

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

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

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.