John the Apostle was one of the Twelve Apostles of Jesus. Unlike the other apostles he died of natural causes in Ephesus in the 2nd Century. His traditional tomb is believed to be located in Selcuk Turkey where Ephesus is located.
According to Roman Catholic tradition, John went to Ephesus after the Assumption and wrote three epistles.
He spent his last years in Ephesus and buried in the southern slope of Ayasoluk Hill. Three hundred years after his death, a small chapel was constructed over the grave in the 4th century. His Basilica was built in the 6th century by Justinian I. It is located on Ayasoluk Hill in Selcuk Turkey which is 3,5 kms (2,2 miles) from Ephesus.
Basilica of St John was in the shape of a cross and was covered with six domes. Being made of stone and brick, it is a rare construction of its period. The tomb of St John was under the central dome, that was once carried by the four columns at the corners. The columns in the courtyard reveals the monograms of Emperor Justinian and his wife Theodora. Rampart walls around the church were constructed to protect it from Arabian attacks in the 7th-8th centuries AD. The impressive 10th century AD frescoes representing St John, Jesus and a Saint ornament the chapel.
With the invasion of Turks, the chapel was used as a mosque in the 14th century but unfortunately the Basilica of St John could not be used anymore due to the serious earthquakes in the same century.
OTTI's Ephesus Tours will give you opportunity to explore Basilica of St John.