This remarkable edifice stands on the south-west side of the Churchyard of Abernethy, a small town situated at some distance from the south side of the Tay, and about three miles west from Newburgh. There can be no doubt that this peculiar form of round tower owes its existence to the presence of the Irish clergy, who returned to Scotland in the ninth century.[137] Abernethy was distinguished as an ecclesiastical site at a very early date, a church having been founded here in the sixth century by King Gastnaid[138] in honour of St. Bridget. Abernethy was then, and for a long period thereafter, the chief seat of the Government of Pictland. In the ninth century, Constantin, the son of Kenneth M‘Alpine, removed the see of the Scottish Bishopric from Dunkeld to Abernethy, where it remained till transferred by Kenneth III., 966-970, to St. Andrews. [Illustration: FIG. 143.--Abernethy Tower. Plans.] The monastery at Abernethy was in the hands of a Culdee establishment in the eleventh century, but about 1200 the church was granted by William the Lion to his favourite Abbey of Arbroath, and the Abbey was secularised. In 1272, the monastery was revived as a Priory of Canons regular of St. Augustine. The once important place of Abernethy has now dwindled into a small quiet country town, of which the ancient Round Tower is the only important feature. The tower stands partly within the churchyard and partly without it, on the east side of the adjoining roadway, and the level of the ground on the side next the latter is two or three feet deeper than that of the churchyard. The doorway (Fig. 143) is situated on the north side of the tower and within the burial-ground. It stands (Fig. 144) about 2 feet 6 inches above the ground, and has had in recent times a few steps built in front of it. The doorway has a plain fillet, 6 inches broad and projecting 2 inches, wrought on the jambs and round the circular arched head. It is 7 feet 8 inches from the sill to the crown of the arch. The jambs incline inwards, the opening being 2 feet 8 inches at the base, and 2 feet 4 inches at the spring of the arch. The round head is hollowed out of a single stone, and the thickness of the wall behind it is arched with several voussoirs. The jambs are each in two stones, which extend through the thickness of the wall. The wall is 3 feet 6 inches thick at the doorway, and the internal diameter of the tower at that level is 8 feet 2 inches. The structure is over 72 feet in height, and is divided in the interior into six stories in the height by projecting string courses, 10 inches by 8 inches, bevelled on the lower side, which carried the joists. There was no staircase, access from floor to floor being by means of ladders. The second, third, and fourth stories are lighted by means of small round-headed and angle-headed windows, with inclined jambs. The top story has four large windows facing the cardinal points. These windows are the most remarkable features of the edifice.