Cryptic messages embedded in the New York City sidewalk.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

One-time winter retreats of prolific inventor Thomas Edison and his friend Henry Ford.

Where dioramas can follow you home.

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.

Former meatpacking facility turned vertical farm and sustainable business complex.

This historic-shipwreck-cum-diving-spot can still be seen poking its boiler out of the Lake Michigan waters that claimed it.

A 19th-century horse lover's bequest led to the construction of this unique fountain in Chicago.

The site of a 19th century "dream city" that almost rivaled Chicago before being swallowed by the Indiana sand dunes.

This spectacular public market has got meat, fish, vegetables, baked goods, and enough kielbasa for a lifetime.

Once the most painted on object in the world, this short campus fence is well on its way to being so again.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

Scores of vintage street lamps shine along L.A.’s Miracle Mile.

A second generation sun-powered marvel lights up the night.

The rustic think-space of famed naturalist John Burroughs stands exactly as he left it.

The oldest continuously inhabited street in America.

A sign at the end of the Santa Monica Pier marks the traditional end of the legendary American highway.

Spinning silently in the lobby of an Art Deco masterwork is a massive vintage model of the Earth.

The competition: breathe deeply as long as you can.

New York City's only radical feminist independent bookstore.

The iconic Manhattan corner that was once the site of the Beastie Boys' fake clothing store.

The oldest surviving synagogue in New York City is now a soaring art space.

Salute the leader of the proletariat.

Love, knishes, and best wishes from this legendary Lower East Side bakery.