Off the south west side of the peristyle was a cult room. This was located in the service quarter. The room had a rectangular plan and was open on two sides due to low walls on the north and south sides of the room. In the centre originally stood a square masonry altar. In the centre of the south wall was a rectangular niche, sitting 1.25m above the floor. The niche was adorned with a marble aedicula façade which consisted of plain rectangular slabs/pilasters on either side supporting a pediment above and a projecting base at the bottom. Within the niche was a low step against the back wall, and a circular depression (presumably for offerings) was present in front. On the pediment was painted an owl, with the Lares painted on either side of the niche holdng rhyton and situla standing between two trees. Above was a garland with taeniae, with birds present above the Lares. Further paintings were present on the eastern wall, containing the famous panel of Bacchus dressed as a bunch of grapes standing beside Mt. Vesuvius. Bacchus was depicted holding his thyrsus which was adorned with taeniae and pouring wine from a kantharos onto the panther at his side. A vineyard/grape vines can be seen growinng on the left side of the mountain. On the other side of the mountain was a bird in flight. Above was another bird perched on a garland of green leaves and red flowers with taeniae. In the lower level of the painting was a single brown and yellow serpent coiling towards a cylindrical altar painted in imitation marble. The serpent was among green plants. A painted dado of imitation marble ran around the room.