Description
In the 3rd or 4th century AD, a Martyrium was built over a tomb, supposedly that of John the Evangelist. A century later, a church with a wooden roof was built over the tomb. This church was damaged by an earthquake and in the 6th century, the Emperor Justinian (527-565 AD) constructed a six-domed church, which became an important place for pilgrimage. Here we see the massive retaining walls that supported the church.