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

There must be a pun in this haystack somewhere...

There are owls with glowing eyes in Herald Square.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Cryptic messages embedded in the New York City sidewalk.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

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

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

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

An Irish Memorial commemorating those who perished due to potato blight.

A field of nothing but boulders which resembles a giant's gravel driveway.

Giant busts of 42 U.S. presidents are sitting in a field in Virginia.

The "lovely red Vega" of the legendary record-settling pilot.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

At 207 feet, one of the world's longest continuous escalators.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

The site of the climactic scene from the classic horror film is now a historic landmark.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

The most decorated dog of World War I is preserved in the Smithsonian.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

Exact replica of the ancient monument, but much, much lighter.

This structure among the trees was the result of divine inspiration.

Memorial built in 1922 in remembrance of WWI casualties.

Step inside Lucy, the world's largest "elephant."