It shall be the responsibility of the owner and occupant of every house or other principle building on any lot in the village to have placed thereon, in a place visible from the street, numerals at least two and one-half inches high, showing the number of the house or building. Properties to which access can be gained from an alley shall have placed on the building that faces closest to the alley, numerals at least two and one-half inches high visible from the alley, showing the number of the house or building. All numerals and backgrounds shall be of contrasting colors.