Anything to add?
Upon a broader look, its main entrance/exit along with its two other sub-entrances/exits were manned with enough people, an alarm system, crisscrossing barricades, a vehicle or two with a mounted gun, and if you'd look through the adjacent buildings, he had other people watching from above with high-powered rifles.
In addition, the other places that might gain entry to the area were closed off from the outside with metal plates—and before going in, an intensive check was needed, including a full body inspection and a washdown.
But yeah, aside from the large open space in the center where college students used to lounge around—which was now being used by his residents for whatever purpose—every other place was just as secure as their entrances.