John on the Island of Patmos
John was a prisoner on Patmos because he was preaching about Jesus and Him raised from the dead. John had this vision about AD95.
The Island of Patmos is a volcanic, treeless, rocky island about 9km by 50 km or 6 by 30 miles. About 30km or 20 miles off the western coast of modern Turkey.
From here John writes to the seven churches. It was where the Romans put the criminals they did not want to escape.Background Reading:
Revelation 1:9-11
John on the Island of Patmos
I, John, your brother and companion in the suffering and kingdom and patient endurance that are ours in Jesus, was on the island of Patmos because of the word of God and the testimony of Jesus. 10 On the Lord’s Day I was in the Spirit, and I heard behind me a loud voice like a trumpet, 11 which said: "Write on a scroll what you see and send it to the seven churches: to Ephesus, Smyrna, Pergamum, Thyatira, Sardis, Philadelphia and Laodicea."
More Information:
John was banished to the Island Of Patmos by Emperor Domitian in 95 CE, and released 18 months later under Emperor Marcus Cocceius Nerva