Glastonbury Abbey was a Celtic monastery founded in the 4th century and enlarged by St. Dunstan and the order of the Benedictines. The original building was destroyed by fire in 1184. The abbey was rebuilt, but fell into ruins after 1539 with the Dissolution of the monasteries by Henry VIII. According to William of Malmesbury and Sir Thomas Malory, Glastonbury is the site of "Avalon," where King Arthur and Queen Guinevere are buried. Another legend relates how Joseph of Arimathea brought the Holy Grail to Glastonbury, where he founded the abbey and commenced converting the ancient Britons.