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.

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

Corn-inthian columns with a uniquely American take on neoclassical architecture.

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

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

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

FDR's Art Deco hospital tower was hopelessly inefficient.

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

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

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

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

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

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

The sculptor was instructed to add “stallion attributes” to the general's bronze mare.

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

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

She stares out across six lanes of traffic, clutching a musket and infant with determination.

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

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

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

Perhaps the most scandalous statue of America's first president.

This taxidermy horse was a Civil War hero.