Sillyon (Greek: Σύλλιον), Stephanus of Byzantium called it Σύλειον, Σύλαιον, Σύλλον and Σίλονον[1] in Byzantine times Syllaeum or Syllaion (Συλλαῖον), was an important fortress and city near Attaleia in Pamphylia, on the southern coast of modern Turkey.

26), the site (recorded as Syllion) was well-fortified and had a strong garrison of mercenaries and "native barbarians", so that Alexander, pressed for time, had to abandon the siege after the first attempt at storming it failed.

In later times, when most of western Asia Minor fell to the Attalid kingdom, Sillyon remained a free city by a decision of the Roman Senate.

3rd-century BC coins feature a bearded head or a standing figure, possibly identifiable with Apollo, or a lightning and the inscription ΣΕΛΥИΙΥΣ (the native Pamphylian name, where И=/w/).

[4] Syllaeum was also located at the start of the great public road that linked the southern coast, via Amorium and Nicaea, with Bithynia and the capital Constantinople.