http://www.wbez.org/series/dynamic-range/demise-building-521-101796

The demise of Building 521 The modernist box at Naval Station Great Lakes couldn't survive changes in military technology. August 18, 2012 By: Robin Amer

This was Gunner School. I went here for about one year of my life. After Basic Electrical and Electronic training. I attended A - School and then System school for the MK - 42 5" 54 Cal weapon system. Of course within a year of reporting to the fleet I lost my Desig. but I still spent 1 year of my life here.

The floors were concrete, and shiny with ten years of wax build up. During rains the building leaked like a sieve drops of water would ball up on the floors instead of spread out as water tends to do when it hit concrete.

I remember the exterior was a glass shell that was suppose to protect the the weapon system inside from the elements. I did a great job with sunlight and snow but by the time I attended there it failed miserably at keeping out the rain. that building drip everywhere. I remember we had a heavy rainfall during my year there. Two students use a couple of boxes of garbage bag to rig up a trough system that would catch the rain and funnel it all to rain barrels placed in different locations.

At the center of the interior was a the school house. A long two story, concrete building. on the top floor was Gunner A school, on the first floor were the classrooms for the various systems the surrounded the school house. The MK 42, MK 10,  and MK 13, are some of the systems I remember. I all I believe there were eight, four down each side of the building, between the schoolhouse and the glass shell.