A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

The longest navigable underground river in the United States is home to countless blind and albino animals.

A stunning, abandoned limestone quarry in southern Indiana provided the stone to erect the Empire State Building.

This national park on the shore of Lake Michigan features remarkable dunes that lie at the heart of a Chippewa legend.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

The only freestanding table rock formation east of the Mississippi.

Train cars and railroad artifacts abound at this restaurant devoted to railway history.

This former Indiana quarry has been transformed into a park and SCUBA site where divers can explore the drowned mining equipment.

A chilling disappearance (and rescue) of a child uncovers a geological mystery.