The Diocese of Llandaff is an Anglican (Church in Wales) diocese that traces its roots to pre-Reformation times as heir of a Catholic bishopric. It is headed by the Bishop of Llandaff, whose seat is located at the Cathedral Church of Saint Peter and Saint Paul in Llandaff, a suburb of Cardiff. It currently covers most of the former Welsh county of Glamorgan, but once stretched from the River Towy to the middle of the Wye Valley.