I live just West of Cheyenne Mountain in Colorado. Years ago you could take a carefully executed and planned tour of a small part of the facility. My husband participated in such a tour. He went thru the huge doors and got to see some of the common areas, and the huge springs. There are no longer tours offered and the area is heavily guarded and considered to be the highest classified area in the military. The United States Space Force is based here as well. 😇