The cities of Lilaia and Polydroso are situated in the valley of the river Kifissos in northern Phocis. Both cities prospered because of their privileged location between two major roads connecting Thessaly to southern Greece. Of all the cities in this region (Haradra-Mariolata, Lilaia-Kato Agoriani, Erochos-Polydroso, Drymaia-Glounista, Amfikleia-Dadi), Lilaia was renown for its abundant water supply, connected since antiquity with the springs of the river Kifissos. In fact, the city was named after the nymph Lilaia, daughter of the deified river. The 'Catalogue of Ships' in Homer's Iliad (B, v. 523) mentions the city in association with the springs of the Kifissos, and Homer's hymn to Apollo records that the beautiful waters of the Kifissos spring from Lilaia and flow before the city. The city's inhabitants also believed that the water of the Kastalia spring at Delphi was a gift from the Kifissos; they placed sweets inside the water on several occasions and believed that these would emerge in the Kastalia. Lilaia is mentioned by Strabo (9.407), Pausanias (10.3.3-5), Ptolemy (3.14.14), and Pliny (Nat. Hist. 4.27).

The earliest traces of habitation in the area date to the Early Helladic period. After the Phocean cities were destroyed by Philip II of Macedon in 346 BC, the city of Lilaia was joined to the neighbouring city of Erochos, which occupied the Agios Vasilios hill and the area of the cemetery of modern Polydroso. Lilaia's fortifications probably date to the period of reconstruction of the Phocean citadels, in the years following Philip II's reign. Traces of early fortification walls, which may pre-date the city's destruction by Philip II, survive at the top of the acropolis.