The town grew up around Côr Tewdws, a monastery and divinity school, alternately named "Caerworgorn", or Bangor Tewdws (College of Theodosius), or later "Bangor Illtyd" ("Illtyd's college"). Saint David, Saint Samson, Saint Paul Aurelian, Saint Gildas, Saint Tudwal, Saint Baglan and king Maelgwn Gwynedd are said to have studied at the divinity school. Côr Tewdws was destroyed in AD 446 and re-founded in AD 508 by St Illtyd as a centre of learning. The ruins of the school are in a garden on the north side of the churchyard; and the monastery was situated north of the tithe barn on Hill Head.