Ayasuluk Hill (Turkish: Ayasuluk Höyük, Medieval Greek: Θεολόγος, romanizedTheológos) is an ancient mound in İzmir Province in Turkey. It forms part of the Ephesus UNESCO World Heritage Site, and is home to a Byzantine fortress and the ruins of the Basilica of St John. It was reputedly the tomb of John the Apostle, the cousin and early disciple of Jesus who is thought to have written the Gospel of John on the site. It became the main settlement of Ephesus after the ancient town declined after the 7th century, following the onset of the Arab–Byzantine wars.