Sure, but Heller Vs. DC affirmed gun free zones.
There have always been “gun free zones”.
Heller stated the obvious but went too far by including schools. That was probably at the insistence of Kennedy, but we cannot be sure.
Weapons have been illegal in prisons forever. They have been disallowed in courtrooms for a long time, but it would be interesting to note when that first started becoming a common practice.
Heller is not perfect. It is simply 1000 time better than what preceded it.