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

The 28,000-year-old specimen is remarkably intact.

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

A much-maligned monument to teetotalism.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

The only Leonardo Da Vinci painting in the Western Hemisphere.

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

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

"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!”

This groundbreaking 16th-century map is known as "America's birth certificate."

This map, on display in the Library of Congress, and one of only seven known to exist, is the very first map of the United States.

This Harriet Tubman mural went viral for kids interacting with it.

The elevator hidden in a smokestack on Roosevelt's yacht now serves as a monument to the former president.

This statue of two men in a rowboat was erected to honor those who died while fishing in the Chesapeake Bay.

An eccentric priest's tribute to George Washington, this chapel tells the story of the American Revolution.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.

The first American department store, and home to the largest operating musical instrument in the world.

This 12-foot bronze statue pays tribute to his early days in Kentucky.

This hidden jockey “walk of fame” celebrates the winning riders of the Kentucky Derby.

Must form and function forever remain at odds? Not if the Florida Department of Transportation has its way.

A psychedelic tribute to one of Georgia's most unique artistic visionaries, out of place and time in the heart of Atlanta.

Mai Tais and Navy Grog served up in one of the original tiki bars.

The first integrated firehouse in Atlanta houses a museum on the history of desegregation in the city's fire department.

Two Civil War-era cemeteries stuck between runways at the world's busiest airport.