ABER LLEINIOG is a defensive structure known as a motte and bailey castle (occasionally mount and bailey). It stands on the left bank of the Afon Lleiniog, about 1.5 miles south of Penmon Priory. Afon Lleiniog, in reality a stream, runs through a fairly steep valley which forms a steep slope up to the castle.
It was first built by Hugh of Avranches, the Earl of Chester, in 1088-90, and is considered an good example of a monument of its type.
Originally a timber castle stood on the mount, on a large artificially constructed hillock encompassed by a dry ditch some 50 foot wide. The height of this mount is about 30 foot from the bottom of the ditch, and its width across the base is about 150 ft. The bailey is placed between the mount and the edge of of the ravine where faint traces of a defensive bank may be seen. Two mounds adjoining the ditch marks its termination. On the mound is a medieval stone structure, now partly restored, about 60 ft square, with a circular tower on three of its corners. The north tower has been restored in earlier times. A fourth tower certainly existed but no trace remains of it. On the north west wall is a projecting garde-robe. Each wall has three buttresses which are additions. There is no trace of the entrance to the site except the approach by the river, and the structure is entered by a break in the south east wall.
This structure is probably late medieval, and is known to have been garrisoned during the Civil War.
The last picture is that of a clump of primroses near the mount, taken on the 12th February 2009.