My paper will demonstrate how the form and location of two major Hellenistic public buildings at Morgantina– the Ekklesiasterion and Bouleuterion– were determined by a much earlier city plan of the mid-fifth century. The refoundation on a new site of Morgantina can now be dated to the decade 459-450 BCE. Features of the city plan reflect the aims and requirements of the widespread contemporary democratic movement that followed on the fall of tyrannical governments in central and eastern Sicily between 472 and 461 BCE. At Morgantina these features included isonomic lot division, an extremely large agora, and an extensive urban area six times greater than that of the older city, implying a much larger population. The new agora reflects the archaic tradition of large public spaces that served for meetings of civic assemblies, as at Kamarina and Selinous; only later did the assemblies regularly turn to theaters as convenient settings for their meetings. Use of the agora at Morgantina for public meetings continued into the early Hellenistic period, as construction of the unusual polygonal Ekklesiasterion in the center of the space demonstrates. The contemporary Bouleuterion housed the Council, the other governing institution; with no convenient place for this large roofed hall in the open agora, one of the isonomic housing lots bordering the public space was chosen as its location. The Hellenistic building program to which both of these meeting places belong was thus adapted to a classical city plan which could not have predicted their form. Undoubtedly, the Hellenistic planners at Morgantina drew on models of building types and settings elsewhere, most probably at Syracuse. Yet the particular solutions that they chose exploited the large canvas prepared two hundred years earlier. Other poleis in the Syracusan Hellenistic kingdom, such as Kamarina, Megara, Akrai, and Tauromenion, had separate histories and appear to have found differing expression for public spaces and institutions.