An abandoned gun-funded 19th century utopia.

Yo, Adrian!

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

Eight "Guardians of Health" protect this art deco water tower from pollutants and bacteria.

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

A bronze statue on a downtown corner honors Minneapolis's favorite career gal.

The "Seinfeld" diner.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

This large midwestern cavern features impressive rock formations and an underground waterfall.

The second oldest Jewish graveyard in the U.S. is tiny, with connections to George Washington and Henry Wadsworth Longfellow.

A giant, Gilded Age mansion that once belonged to the beer baron of Milwaukee.

A town honors its legacy of traditional American Indian pipe carving with one gigantic pipe.

Home of the physician who set the leg of John Wilkes Booth after the Lincoln assassination.

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

The only sea in the world that has no land boundary.

A daily replay of the experiment that proved the rotation of the Earth.

One of America's first spies started out as a teacher in this little red one-room schoolhouse.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

The air force base preserves its scars from the Japanese attack on Pearl Harbor.

More than a century of radio history is told in these displays.

World War II-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.