St. Petroc founded a monastery in Bodmin in the 6th century and gave the town its alternative name of "Petrockstow". The monastery was deprived of some of its lands at the Norman conquest but at the time of Domesday still held eighteen manors, including Bodmin, Padstow and Rialton. Bodmin is one of the oldest towns in Cornwall, and the only large Cornish settlement recorded in the Domesday Book in 1086. In the 15th century the Norman church of St Petroc was largely rebuilt and stands as one of the largest churches in Cornwall (the largest after the cathedral at Truro). Also built at that time was an abbey of canons regular, now mostly ruined. For most of Bodmin's history, the tin industry was a mainstay of the economy.