A church in Winchester where Constans, Arthur’s uncle, was cloistered until Vortigern foisted him to the throne.
Generations later, King Constantine, Arthur’s successor, killed Melou, the traitorous son of Mordred, at the church.
Sources
Historia Regum Britanniae | Geoffrey of Monmouth, c. 1138
Brut | Layamon, late 12th century to mid-13th century