Glasgow was properly established 6th century by Saint Mungo who was a Christian missionary. He built a church on the site where the present Glasgow Cathedral stands today, causing Glasgow to become a religious centre. Prior to this, the area had been inhabited by Picts and Celts and later, by Romans. Romans built outposts and then eventually, the Antonine Wall in an attempt to separate the Romans from the Picts. Remnants of this wall can still be seen today.