sentences:  Less obvious, perhaps, is a group of islands known as the Fortifications, an amphitheatre, an ornamental canal and remains of some avenues of trees.The Fortifications are situated on the Ornamental Waters about 800 yards east of the site of the mansion, to the south-east of the large Lincoln Island.They consist of eight small islands grouped in a circular pattern around a larger central island on which duck-shooting guns were formerly stored.