Whenever and as often as the facts exist which authorize a city to collect taxes from and on any portion of the territory brought within the corporate limits under the provisions of this article, the council or governing body of the city shall pass a resolution declaring the territory (described in the resolution) subject to taxation, and thereupon the mayor or governing head of the city shall make and file with the judge of probate of the county in which the city is situated a certified copy of such resolution, together with a map of such territory attached thereto showing respectively the land owned by the respective owners, if the owners are known, or “unknown owners” where owners are not known.