Photos: Underground at the Titan Missile Museum

The Titan Missile Museum, in Sahuarita, Ariz., about 20 miles south of Tucson, is a former Titan missile launching site. There, crews of four worked 24-hour shifts during which two people always had to be together to ensure safety and security. Here, the tip of the missile--with warhead removed--is viewed from above through a glass window that allows museum visitors to peer down into the silo.