The abbey was founded in the 7th century and enlarged in the 10th, before a major fire in 1184 destroyed the buildings. It was rebuilt and by the 14th century was one of the richest and most powerful monasteries in England. The abbey also controlled large tracts of surrounding land and was instrumental in major drainage projects on the Somerset Levels. The abbey was suppressed during the Dissolution of the Monasteries under King Henry VIII of England and the last Abbot Richard Whiting (Whyting) was hanged, drawn and quartered as a traitor on Glastonbury Tor in 1539.
From at least the 12th century the Glastonbury area was frequently associated with the legend of King Arthur, a connection promoted by medieval monks who asserted that Glastonbury was Avalon. Christian legends have also claimed that the abbey was founded by Joseph of Arimathea in the 1st century.