Quick lesson on Federal Supremacy...
Essentially, the locals can't regulate activity that is already Federally regulated. Thus, a city can't ban overflights by aircraft at altitudes explicitly permitted by Federal regulations. OTOH, the FAR's are silent on where you are permitted or not permitted to land. Therefore, local laws may be passed on the subject of landings on public property. Further, aviation activity on even private property may be regulated by zoning ordinances, as has been done in parts of the Baltimore MD metro area, where the landing of private helos even on private property in residential areas is forbidden unless a zoning variance is obtained (not always easy to do).