4. Black Hills Ordinance Depot

A sprawling military facility dotted with bunkers for miles now stands abandoned in the American heartland of Edgemont, S.D.; experts investigate and uncover a once highly-secure WWII ordnance site designed to store deadly munitions. Further segments of the episode portray the Brushy Mountain State Penitentiary in Tennessee, Wolf House in California, and Pueblo Bonito in New Mexico.