Sillyon is an ancient Pamphylian city and hill-top fortress located 15 kilometers to Serik town today, in Antalya province. It's believed that the city was founded by three heroes after the Trojan War: Mopsos, Calchas and Amfilochos. Another legend says that Sillyon was founded by the settlers from Argos in the Peloponnese. Its Greek name was Sylleion, or Byzantine's called it Syllaeum.

The history of Sillyon dates back to the early 5th century BC, where the city is mentioned in the list of the Delian League as a member paying "symmachikos phoros" (allied tax). In 333 BC Sillyon resisted to the occupation of Alexander the Great's army with its imposing fortifications and location on top of the hill. During the Hellenistic period Sillyon was ruled by the Seleucids, the city was enlarged and many buildings were added. In the 3rd century BC the Pergamon Kingdom ruled the city, giving them an autonomous status. Sillyon minted its own coins during this period. Between 2nd century BC and 4th century AD the Romans ruled the region.

During the Byzantine period Sillyon became an important city; two ecumenical Patriarchs of Constantinople were born there: Constantine II and Anthony I. Also, Christian churches were built during this time. Around 8th and 9th centuries Sillyon became the main city of the region, overshadowing nearby Perge. Finally it was conquered by the Seljuks in 1207. During the Ottoman period farmers settled nearby and some houses were built over and near the ruins.

So far there aren't any scientific archaeological excavations in Sillyon. Most of the city is in ruins dating back to Hellenistic, Roman and Byzantine periods. When visiting the city one can spot ruins of the stadium, Hellenistic walls and fortification towers, entry gate, gymnasium, a 5-meter wide ramp leading into the city, remains of a theater with an estimated capacity of 8 thousand in its heydays, nearby Odeon with almost no traces left, Roman baths, residential area with house ruins, an ancient temple with pillars, Byzantine church, large cisterns, and a couple of old mosques built in the 13th century by Seljuks. Because Sillyon is situated on a hill, you can enjoy great views of wide plains stretching all the way to the Mediterranean. At the entrance of the city there is a fountain named as "Sitma Pinari" made by local villagers, it has a very tasty spring water.