The construction of Oystermouth Castle began in the 12th century, probably around 1107 by William de Londres who had come over to Britain with William the Conqueror. This initial castle was made of wood - easy to construct but also easy to burn.
The Welsh attacked these invaders from Normandy but it wasn't until 1140 that the first stone castle was built (see the red section in the map opposite).
From this time to the early 14th century, there were continual additions (necessitated by the demand for more accommodation) and repairs from continuous attacks).
Each of these phases left their individual marks on the styles of the sections being built.
"Harlech, Caernarfon and other such castles were built over a shorter period and show (roughly) similar styles throughout. Oystermouth Castle is far more interesting as you can walk through and see / feel the different periods of history. You can feel the battles and see first hand the growth according to the wealth and influence of particular lords at the time." Visitor to the Castle
Courtesy Roger Parmiter