One of the most impressive features of this castle, and one that makes it unique in the British Isles, is the solitary, round tower. This is a typically French architectural feature, and Edward stayed at French castles (for example, Aigues-Mortes) that have this feature on his way to the Eight Crusade. This unique layout in British castles can be clearly seen in the Google map to the right. One of the four corner towers is both enlarged and removed from the rest of the ward. The stand-alone structure at Flint was then used as a corner tower and a keep or dungeon.