The council shall have authority to determine and establish the grades of all streets, avenues, alleys and public grounds within the city, and to require improvements and buildings adjacent to or abutting upon such streets, alleys or grounds to be made and constructed in conformity with such grade and upon such line as shall be prescribed by the council; and the council may change or alter the grade of any street, alley or public ground, or of any part thereof, whenever in their opinion the public convenience will be promoted thereby. Whenever a grade shall be established or altered, a record and diagram thereof shall be made in the book of street records in the office of the city clerk.