The settlement which will later be named Palermo was placed in an ideal position: at the margins of a vast plain surrounded by mounts and commanding a wide bay. Such geographical features, along with plenty of water from rivers and streams offered the perfect setting for agricultural and commercial activity. One spot in this idyllic context was particularly favourable, and this was a slip of terrain at the confluence of two streams, the Kemonia and Papireto, that still flow underneath the modern city. The two rivers joined in a small inlet (modern Cala) offering additional protection for ships and boats, and gave the city the name of Pan-ormos, that is Greek language for “all harbour”.
The short slip between the two rivers was a natural stronghold, easily defensible with water on three sides and a little, narrow hill on the remaining one. During the 8th century BC, a Punic colony was established on the little peninsula and during the following century a strong wall circuit was built all around the settlement, remains of wich can still be seen under the Royal Palace and in other spots in the city centre. This fortification wall, with tall towers, was so powerful that it held back Dionysius of Syracuse when he tried to capture the city at the end of the 5th century BC.
During this period the city was divided into two parts: the Paleapolis (“ancient city”) on and around the rocky hill to the north, and the Neapolis (“new city”) towards the sea. The road pattern was dominated by one main road, more or less under the upper part of modern Corso Vittorio Emanuele, and a series of narrower roads like a fish-bone, some of which still survive in the plan of the modern city centre (e.g. Via Celso, Via Biscottai). Outside the city walls, like in every ancient city, there was the main necropolis with chamber-tombs carved into the rock. The port was fully equipped to maintain a Punic fleet of at least 40 triremes, like the one that in 406 BC took part in the siege of Akragas under the command of general Imilcon.
After many attempts to capture the city, it was eventually taken by the Romans, after a long siege, in 254 BC. The change did not affect the wealth of the city that thrived even more under Roman rule, as attested by the splendid remains of patrician homes (domus) in Piazza della Vittoria and behind the Cathedral. The city remained a commercial center during alla of the Roman period and wares coming from all over the Mediterranean were exchanged in its markets. Remains of Punic and Roman amphoras, along with lead anchors bearing the merchant marks of roman citizens are preserved in the Archaeological Museum to bear witness of this chapter of the economic history of the city.
During the 5th century AD all of Sicily is threatened by the incursions of the Vandals led by king Gensericus, who take advantage of the disgregation of the Western Roman Empire. After a desperate resistance in 444, Palermo is sacked as well. In 491 the city is again taken by the Ostrogoths and the fortification system is enhanced under their rule. This is not enough to prevent the Byzantines of general Belisarius to retake control of the city in 535 and grant its populace a period of relative security. Under the Byzantines the city regains its influence and at the end of the 6th century pope Gregorius the Great establishes Palermo as head of all western Sicilian churches, recognising the role of its Christian community. Signs of early Christian activity in the city are some Catacombs (e.g. the Catacombe di Porta d’Ossuna) and hypogeic chambers and churches in the banks of the Kemonia river. This influence must have gone even further if in 672 the Holy See itself is occupied by a cleric from Palermo, pope Sergius I.