Grumentum developed in the upper Agri Valley of ancient Lucania during the early third century BCE. Its position near routes linking inland southern Italy with the Ionian and Tyrrhenian coasts gave it military and commercial value. Initially a Lucanian center allied with Rome, it became entangled in the Second Punic War. Livy describes fighting near the city, including a Roman encounter with Hannibal’s forces in 207 BCE. These conflicts placed a regional settlement within the wider struggle for control of Italy.

Romanization proceeded through land division, citizenship, and new civic institutions rather than one sudden replacement of local society. Grumentum suffered during the Social War in the early first century BCE, then recovered through reconstruction and promotion as a Roman colony. From the later first century BCE, builders imposed a monumental urban plan along paved streets. The forum gathered the capitolium, imperial cult buildings, porticoes, basilica, curia, and administrative spaces that announced the community’s place within Roman political and religious life.

Public entertainment and bathing occupied prominent areas. A theater stood beside a richly decorated house and an Italic-style temple. The amphitheatre, built around the middle of the first century BCE, is among the older surviving masonry examples and used the edge of a natural slope. Large baths contained heated rooms, hypocaust systems, mosaics, imported marble, and water infrastructure. Houses, workshops, drains, gates, and cemeteries complete the picture of a city shaped by local agriculture, regional roads, public generosity, and imperial culture.

Grumentum remained occupied in late antiquity and became an episcopal seat in the fourth century. A Christian basilica, later associated with Santa Maria Assunta, marked the transformation of civic and sacred space. From the fifth century, public buildings were increasingly abandoned or reused, and burials appeared within the former city. Insecurity, economic change, and raids encouraged settlement on higher ground. A smaller population endured for centuries, but the valley city eventually gave way to communities including the hill town now called Grumento Nova.

Modern excavation has made the street grid and major districts unusually readable. The archaeological park preserves the theater, mosaic house, temples, forum, baths, basilica, roads, and amphitheatre within a broad landscape overlooking the modern Pertusillo reservoir. The nearby National Archaeological Museum of the Upper Agri Valley displays finds from Grumentum and surrounding territory. Together they reveal a complete urban sequence: Lucanian settlement, Roman ally, colony, monumental city, Christian bishopric, and abandoned center whose fields protected foundations for archaeological study.