The ancient acropolis of Panopeas dominates the hill above the settlement of Agios Vlasios. Of the entire ancient Mycenaean period fortification that surrounded the acropolis, only some parts of the wall and some towers survive.

Homer (ancient legendary author of the epic poems of Iliad and Odyssey) mentions in the Iliad that the builder of the notorious Trojan Horse was the Epeus, son of Panopeas. The acropolis of Panopeas was first inhabited in the 18th century BC, and during the Mycenaean period it was fortified with cyclopean walls. The city was refortified with strong walls shortly before the great battle of Cheronia in 338 BC.