No building or structure shall be erected, altered, restored, or moved within the historic district until after an application for a certificate of appropriateness as to exterior architectural features has been received by the Commission and approved by said Commission. No building permit for erection of a building or structure or for alteration of an exterior architectural feature within a historic district and no demolition permit for demolition or removal of a building or structure within the historic district shall be issued by the Town of Harwinton or any department, agency, or official thereof until a certificate of appropriateness has been issued. A certificate of appropriateness shall be required whether or not a building permit is required. The style, material, size and location of signs and fences within a historic district shall also be under the control of such Commission. In addition, the Commission shall exercise such other authority granted to it by law.