Looks like the control house and maybe a silo for one of the ICBM's. There are a bunch on the northeastern plains in Colorado. There is also an old altas missle complex for sale near Denver. Three silo and one control complex for about 1.6 mil. Should see some of the homes they built into those.
If you hang around long enough here the maintenance crews will be around in their govt vehicle. Armed guards and the works. Or you could hop the fence and see what happens.