Castell Aberlleiniog (Castle of the Mouth of the Lleiniog) is a motte and bailey fortress near the Welsh village of Llangoed on the Isle of Anglesey, built between 1080 and 1099 by Hugh d'Avranches, 1st Earl of Chester. It is about two miles distant from Beaumaris Castle, and was built atop a very steep hill.
Castell Aberlleiniog is built in a strategic position beside the Menai Strait opposite the Norman castle at Abergwyngregyn, showing that visual communication was important to the Norman invaders. It was probably erected by Hugh d'Avranches, 1st Earl of Chester, when he conquered Gwynedd in 1088. There are few historical documents that detail the events the castle has seen through its life, however some do survive, including a record of a siege in 1094 by Gruffudd ap Cynan on his return from Ireland. The siege was successful, 124 Norman defenders died in the battle. Gruffudd was later successful in driving Hugh out, and after this, Anglesey remained under the control of the Welsh until the arrival of Edward I two hundred years later. It is not known whether they made use of Castell Aberlleiniog.
The original Norman timber structure is long gone, replaced by a stone structure at some point prior to the mid-17th century, when it was destroyed by Thomas Cheadle, the constable of Beaumaris. The site was restored from 2008 and is (2016) open to the public. The keep had broad ramparts fronted by a narrow wall rising to a parapet; each corner contained a round tower, the remains of which can still be seen.
References:Château de Niort is a medieval castle in the French town of Niort. It consists of two square towers, linked by a 15th-century building and dominates the Sèvre Niortaise valley.
The two donjons are the only remaining part of the castle. The castle was started by Henry II Plantagenet in the 12th century and completed by Richard the Lionheart. It was defended by a rectangular curtain wall and was damaged during the Wars of Religion. In the 18th century, the castle served as a prison.
The present keeps were the central point of a massive fortress. The southern keep is 28m tall, reinforced with turrets. The northern tower is slightly shorter at 23m. Both are flanked with circular turrets at the corners as well as semicircular buttresses. Each of the towers has a spiral staircase serving the upper floors. The Romanesque architecture is of a high quality with the dressed stones closely jointed.