Idaho Code § 58-905

In any action for the possession of, or for any injury done to, a lot or parcel of land, situated in any city, town or village on the public lands, the plaintiff must be required to prove either an actual inclosure of the whole lot claimed by him, or the erection of a dwelling house or other substantial building on some part thereof, by himself or some person through whom he claims, and proof of such building, with or without inclosure, is sufficient to hold such lot or parcel to the bounds thereof, as indicated by the plat of such city, town or village, if there be one, and if there be no such plat, then to hold the same, with its full width and extent from and including such building to the nearest adjacent street, where the intervening space has not been previously claimed by adverse possession.