The oldest continuously inhabited street in America.

Quirky castle designed by the American actor best known for portraying Sherlock Holmes on stage.

Ancient petroglyphs discovered only after a massive fire swept across Michigan in the 1880s.

The world's longest known cave system.

Memorial built in 1922 in remembrance of WWI casualties.

A tribute to Ponce de Leon's supposed quest for eternal youth.

A fence constructed completely of skis on Monroe Street.

Moonbows over Kentucky.

Oldest unrestored plantation house in America that is open to the public.

This "life-size" depiction of Mickey Mouse as a half-lobster is both whimsical and a bit creepy, standing guard over the Boston waterfront.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

Commonly referred to as the most photographed Victorian home in the United States.

Oldest existing church in New York and the inspiration for Washington Irving's "The Legend of Sleepy Hollow."

Haunting and beautiful trees, doomed to die.

Only known mainland rookery of the threatened Stellar sea lion.

Former bath house turns gastropub.

The only arched bridge made of stone on the entire Mississippi River.

Where Cusack's record store from the film "High Fidelity" was located.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

A "haunted" landmark on the coast of Southern California.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

A volcanic fissure over two miles long and up to 70 feet deep.

A Roman-style column in Oregon hides a spiral staircase inside.

A place to eat for on-the-run agents and espionage enthusiasts.