An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

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

Inside houses a vast collection of military aircraft and missiles spanning the ages.

This stuffed pigeon of war had the very serious name "John Silver" until he lost a leg in battle.

A real flying saucer, contracted by the U.S. Air Force.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

The childhood home of the Wright Brothers in Dayton.

This small museum celebrates the father of modern skiing, as well as Norway's other notable contributions to skiing.

Copenhagen's "other" little mermaid marks the historic location of past sea maid sightings.

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

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

"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!”

Home to items never before seen by the public.

A historic neighborhood church is reborn as a psychedelic arts collective.

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

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.

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

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

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

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Classy up your Big Mac with bow-tied servers and chandeliers at the world's fanciest McDonald's.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

An overgrown collection of miniature buildings still stand as evidence of one couple's obsession with The King.

This collection of over 50 classic pinball machines awaits visitors to downtown Roanoke.