More than five miles of underground passageways.

All that's left of the quintessential "cabin in the woods."

Home of an evil witch famous within southern folklore.

Enormous lake at the bottom of a unique cave system.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

The birthplace of America's favorite fruit-flavored mystery dessert.

The notorious headquarters of a corrupt political machine.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

Steepest flood safety railway in the entire world.

This stone tower marks a lookout point over the historic Washington Crossing, and maybe some buried treasure.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

The lowest point in South Dakota and the source of the Minnesota River.

South Dakota's oldest operating brewery is housed inside a historic firehouse.

This geodesic gallery holds a collection of painted spheres that make traditional canvases look lazy by comparison.

One of the world's most definitive collections of musical instruments, spanning all cultures and historical periods.

The highest point in South Carolina was once owned by an energy company that neglected it but now the state is taking it back.

This titanic steel chain linking two buildings was installed without permission but instantly beloved.

A rapidly disappearing authentic bit of the old south.

Charleston's historic city jail once held everyone from pirates to Civil War POWs.

Off a hiking trail in Rhode Island stands a picturesque memorial to a long-forgotten war.

As state high-points-by-elevation go this spot is one of the lowest, but for years it was also the hardest to climb.

This historic Rhode Island mini-cemetery features a number of headstones run through with mysterious holes.

A massive forgotten storehouse from 1913 on the Brooklyn Waterfront has a spectacular view of Brooklyn.