This is the Stanley R. Mickelsen Missile Complex located near Nekoma, ND. Built in the early 1970s, it provided radar and missile control for up to 100 anti-ballistic missiles. It was operational for less than a year before being shut down in 1976.
Viewing the pyramid through the towers
Looking to west at what is left of the support buildings for the site
The radar pyramid along with the cooling towers for the underground diesel generators