The Norman invasion of Ireland began in 1169 when Pope Adiran IV wanted to excerpt control over Celtic Christianity. To protect his Norman stronghold, William Marshal, the 1st Earl of Pembroke, began creating a network of walls encircling Hightown in the late 13th century. When it was finished in 1352, the defense measured almost one mile and enclosed 69 acres. Additional fortifications continued through the mid-17th century, long after the Norman Wars ended in 1541. A few pieces of the walls remain. The longest section – over 300 feet – is near the Black Abbey. Elsewhere, the former perimeter is marked with occasional plaques. Maps are available if you want to walk along the boundaries of the medieval town.