A city of the primary class shall have the power to (1) remove all obstructions from the sidewalk, curbstones, gutters, and crosswalks at the expense of the owners or occupants of the grounds fronting thereon or at the expense of the person placing such obstructions there and (2) regulate the building of bulkheads, cellars, basements, stairways, railways, windows, doorways, awnings, lampposts, awning posts, and all other structures upon or over adjoining excavations through or under the sidewalks of the city.