39.2435°N 22.2731°WProerna (Greek, Ancient (to 1453);: Πρόερνα) was a town and polis (city-state) of Phthiotis, in ancient Thessaly.[1] Strabo lists the town between Thaumaci and Pharsalus, in Phthiotis, but otherwise provides no indication of its exact location. Stephanus of Byzantium writes Proarna (Προάρνα), and calls it by mistake a town of the Malians. In 191 BCE, Proerna, which had been taken by Antiochus III, was recovered by the consul Manius Acilius Glabrio during the latter's advance through Thessaly, a little while before the Battle of Thermopylae. We learn from this passage of Livy that Proerna stood between Pharsalus and Thaumaci.
The site of Proerna has been located at a place called Neo Monastiri (meaning, "new monastery") in the territory of Gynaikokastro.