R.I. Gen. Laws § 44-3-43

The city and town councils of the various cities and towns may provide, by ordinance, an exemption not exceeding five thousand dollars ($5,000) of valuation for any parcel of real property on which is located an historic stone wall(s); provided, that the wall(s) is fifty (50) or more feet in length, at least three (3) feet high, structurally maintained and free of noxious weeds and vegetation. For purposes of this section, an “historic stone wall” is a vertical structure of aligned natural stone built before 1900, normally constructed to designate a property boundary or to separate agricultural activities within a farmstead.