File:Aerial view of the city of Dion, Ancient Dion (7094436303).jpg

The existence of the revered sanctuary of Zeus Olympios was the principal reason for founding the city named after the god, Dion adjacent to the sanctuaries. Textual sources and archaeological finds bear witness to the presence of a sizeable settlement already in the second half of the 5th century BC. The enhancement of Dion as central sacred place of the Macedonians contributed to the development of the city, which in Hellenistic times was famed and wide for its fortification and its splendid monuments. Built on level ground and square in shape, its urban plan was laid out according to the Hippodamean grid system. Because of the several successive building phases in the city, the remnants dating from the Hellenistic period are found at great depth.

In 169 BC Dion was captured by the Romans consul Marcius Philippus. Shortly after the naval battle of Actium (30 BC), Roman citizens settled in the city, founding a colony officially named Colonia Julia Diensis. Dion enjoyed an economic and cultural heyday during the 2nd and in the early 3rd century AD. There are strong signs of a renaissance of Classical Greek civilisation and a revival of memories of the time of Alexander the Great. In this period there was extensive rebuilding of the political centre of the colony, with the construction of luxurious public and private edifices.

The epicenter of public life in Dion was always at the south entrance to the city, next to the gateway leading to the sanctuaries. The main road (cardo) of Dion ran through the city from north to south, linking the corresponding gateways in the wall. It was charted in Hellenistic times bu was not paved until the 3rd century AD. The excavation of porticoes along the kerb revealed that this street was a via colonnata.