"Llanilltud Fawr" is named for the Llan of Saint Illtud, the Llan was home to the Monastery of Illtud and the College known as Côr Tewdws. Llantwit would grow into one of the most esteemed centres of Christian culture in the Celtic world. At its peak it attracted over 2000 students, including princes, numerous eminent clergymen and revered saints. The institutions were destroyed by the raiding Vikings in 987, but the monastery was rebuilt by the Normans in 1111 and continued to be a centre of learning until it was disbanded in 1539 during the Dissolution of the Monasteries. The 13th-century St Illtyd's Church, built near the ancient monastery, is a Grade I listed building and one of the oldest parish churches in Wales.