The area around Aberystwyth formed a natural harbour on the Welsh coast, especially before silting and later development changed the river. Ships could gather there in relative safety, making the site valuable for maritime movement as well as landward control. Water around the site made it easy to build moats and other obstacles, while nearby hills strengthened the defensive position. Holding the castle meant controlling this sheltered gathering place for ships. Its plan had to conform to the geography, whereas Beaumaris offered more freedom over the layout.
Notable Point · 14:31-15:57
Natural harbour and defensive geography
The natural harbour, river, water obstacles, and defensible hills explain why a major castle belonged at Aberystwyth and why its plan followed the terrain.