This chapter is enacted under § 62.23, Wis. Stats., to promote the public health, safety, morals and general welfare; to regulate and restrict the height, number of stories and size of buildings and other structures, the percentage of lot which may be occupied, the size of yards, courts and other open spaces, the density of population, and the location and use of buildings, structures and land for trade, industry and other purposes, and for such purpose to divide the City into districts of such number, shape and area as are deemed best suited to carry out such purposes; to provide a method for administration and enforcement; and to provide penalties for violations.