Walk west about 20 minutes from the acropolis across the now-dry river Modione (formerly the Selinon), then up a dirt path, and you'll reach the ravaged ruins of the temple dedicated to Demeter, the goddess of fertility. Amid the debris, two altars can be made out; the larger of the two was used for sacrifices.
Although they're not much to look at, these are some of the most important finds of the site as they provide an insight into the social history of Selinunte. Thousands of votive offerings to Demeter have been found in the area (nearly 12,000), including stelae crowned with real human heads.