Thyraeum or Thyraion (Greek, Ancient (to 1453);: Θυραῖον) was a city in ancient Arcadia, Greece, in the district Cynuria. According to Greek mythology, it was founded by Thyraeus, a son of Lycaon. It was already ruined in the 2nd century, when it was visited by Pausanias.[1] It was near Hypsus (present Stemnitsa), Zoetia and Paroria.
Its site is tentatively located near modern Syrna.