Hmmm... I spent 15 hours totally working yesterday (8 on, 8 off, 8 on) and had figured out the most fortified building in the entire complex in case of a zombie attack. . . Part of the complex is on an island with 2 bridges for access... one of them gated. On the bridge there is a condo complex, with several layers of gates to get in and to the top of the building... where I would have a perfect line of site on both entrances to the island.
Oh well... maybe next time