The Council shall have authority to layout, open, widen, extend, straighten, alter and improve streets and alleys, by grading, graveling, surfacing, curbing, paving, draining, repairing, repaving, illuminating, maintaining the same free from dust and nuisance and/or otherwise. The word "street" as used in this Charter shall include all public highways by whatever name known, except alleys, unless the context otherwise indicates.