The mayor and city council of any city of the first class shall have power to make contracts with and authorize any person, company, or association to erect a gas works, power plant, electric or other light works, heating plant, or waterworks in such city and give such persons, company, or association the privilege of furnishing water, lights, power, or heat for the streets, lanes, alleys, and public places and property of such city and its inhabitants for any length of time not exceeding twenty-five years. Any city of the first class may by resolution of the city council contract for the furnishing of electricity at retail to such city and the inhabitants thereof with any public power district, or an electric cooperative which cooperative has an approved retail service area adjoining such city’s retail service area.