The commission shall have the authority to disapprove any proposed building or structure, or any change in an existing building or structure which, in its opinion, would have detrimental effect on the appearance of the area under consideration. The commission may require changes in the architectural treatment of buildings or structures, and may require additional landscaping and development improvements as are necessary in its judgment to carry out the intent and purpose of the civic design district. (Ord. 1000 § 22.67, 1955)