The zoning regulations and districts as herein established have been made in accordance with a comprehensive plan and designed to lessen congestion in the streets; to secure safety from fire, panic and other dangers; to promote health, safety and the general welfare; to provide adequate light and air; to prevent the overcrowding of land; to avoid undue concentration of population; and to facilitate the adequate provision of transportation, water, sewer, schools, parks and other public requirements. They have been made with reasonable consideration, among other things, for the character of the district and its particular suitability for certain uses, and with a view of conserving the value of buildings and encouraging the most appropriate use of land throughout the city.