Fig. 185.—Ground plan of Broch of Kettleburn, near Wick, Caithness. (From a Plan by Mr. A. H. Rhind.) ] When fully cleared from the ruin of its upper portion, the lower part of the building showed a circular construction (_b b_ in the accompanying plan, Fig. 185), consisting of a wall 15 feet thick, surrounding a central area of 30 feet diameter. The doorway (_e_) passing straight through the wall, was flanked by a guard-chamber (_t_) on either side. Remains of two oblong chambers (_r_, _i_) constructed in the thickness of the wall were also found some distance apart. The roofs of all the chambers were gone, but the lintels remained on the passages leading into them. There was a well with steps leading down to it in the central area. It was 9 feet deep, and being covered for the support of a partition wall (_p p_) which passed over it, was full of good spring water when discovered. The area enclosed within the circular wall of the Broch was subdivided into irregularly-shaped spaces (_m_, _s_, _o_) by walls built across it in various directions, and abutting on the main wall. I shall have more to say of such irregular constructions within and around these towers when we come to deal with them in other cases, which show that they are secondary constructions, built out of and upon the fallen materials of the primary edifice. The area outside the tower for a distance of 25 feet from its external wall was covered by the ruins of similar irregular constructions (_c d_), and the whole was surrounded at that distance from the central tower by a wall (_a_) 3 feet thick, of whose height little more than the foundations remained.