Prison built by Acme building corporation

This was one of the finest prisons mankind has ever built. What with the free unguarded access the prisoners had to virtually any single place inside the whole prison including other prisoners' cells, the roof of the prison and the warden's office you could just waltz into if you wanted to squeeze the warden's neck et cetera. This ingenious design isn't only limited to rooms though. You'd have to be stupid not to understand why the prison guards handgun has exactly three bullets before it runs out, but I suppose anything more is just showboating.