Viking time, was found in the upper part of a mound covering the ruins of a Broch at Castletown, in Caithness. I found a single burial in a stone-lined grave laid close to the doorway of the Broch of Brounaben, not far from Yarhouse; and burials were found in the mounds covering the ruins of the Brochs of Thrumster and Dunbeath, in Caithness. It is therefore probable that in all such cases the interments that are found immediately below the surface of these mounds belong to a time when the Broch had been so long in ruins that it appeared to those so using it as a natural grassy knoll. [Illustration: Fig. 196.—Interior aperture of Doorway in Broch of Yarhouse. (From a Photograph.)] [Illustration: Fig. 197.—Entrance to the stair and window-like openings over it, in the Broch of Yarhouse. (From a Photograph.)] When excavated, the Broch of Yarhouse consisted of a circular wall, 12 to 13 feet thick, enclosing a central area, 30 feet in diameter. The height of the wall remaining was about 15 feet. The doorway which passes straight through the wall is about 6 feet high and 2½ wide, slightly narrower at top than at bottom, and well built with long flat slabs, some of which were 8 feet in length. The opening of the doorway into the interior area and recess above it are shown in Fig. 196. There were no guard-chambers or bar-holes, and the checks for the door were quite on the inner side of the wall. But this Broch stood on what was practically an island, cut off from the land by a ditch 25 to 30 feet wide, and the access to the doorway was carefully protected by the outworks to be subsequently described. Opening from the interior area to the left of the doorway was the entrance to the stair (Fig. 197), which also gave access to an oblong chamber at the stairfoot. The stair itself was 3 feet wide, and 16 steps up there was a landing, with a light hole or window looking into the interior of the Broch. Above the entrance to the stair there were also three windows, placed vertically over each other—all that remained of a vertical range of windows, such as we have seen in the case of Mousa, Dun Carloway, and the Glenelg Brochs. On the side of the area opposite to the doorway was an oblong chamber in the thickness of the wall, roofed in the usual manner by overlapping stones. In this Broch, as at Kintradwell, there was an interior wall, of inferior masonry, built against the main wall, and partially bonded into it at the door openings. This inner wall was 2½ feet thick, and rose to a height of 8 feet, where the wall-head formed a level scarcement all round the interior. Partition walls (shown at B in ground plan, Fig. 194) ran half way across the area from both sides of the doorway, and that on the right of the entrance bent at a right angle towards the Broch wall. These partitions were partly built, and partly formed of long slabs set on end. They rose to about 8 feet—the same height as the scarcement.