D.C. once had its own tiny rival to the New York Stock Exchange.

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

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

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

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

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

A secret greenspace hides atop a Capitol parking garage.

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

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

A much-maligned monument to teetotalism.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

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

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

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.

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

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

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