Three semicircular exhedras open onto a large, square central hall. The central part is decorated with mosaics depicting the Twelve Labours of Hercules, for example the Hydra of Lerna, with Hercules depicted cutting off its heads. At the centre of the left semicircle is a picture showing the glorification of Hercules, and the central semicircle portrays an impressive gigantomachy, a combat during which five giants perish under Hercules' arrows; while the legend of Ambrosia and Lycurgus is illustrated in the right semicircle.