Against the northern wall of the garden stood a nymphaeum. This took the form of a large aedicula with a vaulted niche on its southern face. The entire structure was decorated in glass tesserae and shells. The decoration included large panels such as the central panel of ducks and fish on the rear wall of the niche with Neptune holding a trident in the centre. In the vault of the niche was a half-naked Venus lying in a shell. On the façade, flanking either side of the niche, were two small mosaic masks, and two cupids holding reeds and a sceptre. A tailed figure was present in the centre of the tympanum. Shells were used to outline the different sections of mosaic decoration. In front of the structure was a small rectangular pool, which was painted blue on its interior.