§ 26. Official map, establishment. Every city by ordinance, local law or resolution of the legislative body which has the authority to lay out, adopt and establish streets, highways and parks may establish an official map of the city showing the streets, highways and parks theretofore laid out, adopted and established by law. Drainage systems may also be shown on this map. Such map is to be deemed to be final and conclusive with respect to the location and width of streets, highways, drainage systems and the location of parks shown thereon. Such official map is hereby declared to be established to conserve and promote the public health, safety and general welfare. Said ordinance, local law or resolution shall make it the duty of some appropriate official or employee of said city at once to file with the clerk or register of the county or counties in which said city is situated a certificate showing that the city has established an official map.