In addition to the 16 Sprint missiles at the MSR complex, another 54 Sprints were dispersed among four Remote Sprint Launch sites or RSLs. From srmsc.org:

"The RSL's were designed to place Sprint launchers as close as possible to the trajectories of target re-entry vehicles to minimize the time from launch to interception during the critical time constraints of terminal defense. The four sites were arrayed around the central MSR complex in roughly northeast, northwest, southeast, and southwest directions. Approximate distances from the MSR complex were 10 miles to the closest RSL (#4), and 22 miles to the most distant (#3). (See map.) Like the PAR and MSR, the RSL's were hardened against nuclear blast effects and were capable of operating autonomously while "buttoned up" during a nuclear attack.

A total of 54 Sprint launchers were distributed among the four RSL's: 1 (12), 2 (12), 3 (16), 4 (14)."

Jerry Greenwood met me at RSL #3, just east of Langdon, ND.  According to Jerry, of the four RSLs, #3 remains truest to its original configuration and could conceivably be turned over to local authorities at some point to further preserve the historic qualities of the site. Indeed, other than some asphalt deterioration, the surface area of the site is in pretty good shape and the grass had recently been cut.

The entire site is surrounded by a low perimeter fence which encloses another three layers of security fencing. Entry is made through a sally-port at the main sentry station. A smaller sentry station further limits access to the Sprint missile field.

The Sprint launch cells were topped with a fiberglass cover which would be explosively broken just prior to launch. The actual missile launch involved the ejection of the two-stage Sprint from its cell by a gas-fired piston. As the missile cleared the surface, the first stage ignited and Sprint was tipped towards its target by vectored thrust.

Next stop is the Remote Launch Operations Building (RLOB). The RLOB is an underground, reinforced concrete structure used to support operations at the RSL. The entrance is an above ground portal which leads into a concrete-lined access tunnel. The RLOB is hardened against nuclear blast and contains the underground power plant, communications equiment,  mechanical equipment, security center and living quarters.

As expected, water has found its way into the RLOB. Fortunately, someone had left a pair of rubber boots just inside the entrance so I was able to slosh around inside. There appear to be two rolling steel blast doors at the lower building entrance as well as a swinging blast door leading to an offset area for personnel decontamination. 

There are numerous equipment rooms along the main corridor which housed the generators, air handlers, communications equipment and so forth.

Towards the end of the main corridor is the security station which would have been staffed by MPs armed with M-16s and sidearms. There is still a very cool piece of artwork on the front of the security desk showing crossed, flintlock dueling pistols over a Sprint missile.