Metropolitan Park is indeed owned by the City of Jacksonville. The question of whether a landlord (Jax) can convey a privilege (banning of lawfully carried firearms) that they, themselves do not possess (through preemption) is a question that is ripe for trial, but has not yet been addressed in the courts. Florida Carry's legal team has weighed in on the question, concluding that indeed, a public property leased to a private concern remains public property. Another small detail is that you'll notice "weapons" are prohibited. Per §790.001 Florida Statutes, a firearm is not a weapon. I will be forwarding your post to our Jacksonville lawyer to see if he wants to attend the event.