The enceinte, which is dated from excavational evidence to the first building phase about 300 B.C., was probably the work of Kassander. It had a solid toichobate, constructerd of a single course of roughly dressed stones and one or two courses of finely dressed blocks, on which rested a wide wall made of unbacked bricks; at intervals the enceinte had square towers for more effective defence. The regular square plan was interrupted on the east side by a long narrow projection, which semms to have been designed to dam the flow of the river Vaphyras, which in antiquity was navigable, and which may have been due to the existence at this point of a harbour. The classical defences were probably destroyed in 220 B.C., when the macedonian sanctuary was plundered by the enemies of Philip V, the Aitolians, under their general Skopas.

They were obvisously quickly repaired - presumably by the father of Perseus himself, and in an exemplary fashion - in view of he impression made by the defence works on the Romans when, in 169 B.C., shortly before the battle of Pydna, they entered the abandoned city.

Down to A.D. 250, the walls of the Colonia Iulia Diensis do not appear to have attracted the interest of the Roman overlords. It was only at the beggining of the second half of the 3th century A.C., when the barbarian Gothic tribes flooded into the Balkns, that concern was shown to fortify Dion. Building material taken from demolished structures of more glorious times, altars, marble statues and architectural members, now formed the raw material for this hasty contruction.

The final phase of the defences, the work perhaps of the middle of the 4th century A.D., has haracteristic masorny of rubble bound together with lime and framed with fragments of tile. The enceinte is dinstinctly smaller (length of walls 1.600 m., area of 155.000 sq.m.) and included only a part of the formerly flourishing city. The final destruction of the city was not long in coming: as early as the middle of the 5th century A.D., Dion began to become a city of the past.