Knoxville’s architectural icon was the symbol of the 1982 World’s Fair, even catching the googly eye of Bart Simpson.

A recreation of the doomed ocean liner in the middle of the Smoky Mountains.

A farm in New Jersey grew a most unusual crop for AT&T's testing purposes.

A historic grist mill and active sluice on the Black River.

This historic building housed the surviving crew members of the Titanic, who were left destitute after the wreck.

A plaque immortalizes the spot where the early American spy said his famous last words: "I only regret that I have but one life to lose for my country."

Discover the taste of mold.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

A grand New York post office that is home to mailman Santas, scraps of postal history, and a pneumatic mail system.

A bit of retro transportation flair preserved in the world's largest department store.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Cryptic messages embedded in the New York City sidewalk.

The rough and tumble president's childhood home displays the shirt he was once shot in and the speech that saved him.

The only subway station in the city that still makes use of gap fillers.

The rare American Civil War-era weapon was never fired in anger.

On the hills of Bay Ridge stands a house straight out of a fairy tale.

A hip bar decorated with walls of golden skulls.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

The final home of the most famous horse of the American Civil War.

One of the most important yet well-hidden museums dedicated to the history of medicine.

Plaques on its facade commemorate the Tiber's most destructive deluges.

Architectureal fantasy quarter of Rome.

The world's longest known cave system.