The first bridging point on a navigable, defensive barrier, great river and the foundation in 681 of the abbey of St Peter by Æthelred of Mercia, favoured town growth; and before the Norman conquest of England, Gloucester was a borough governed by a portreeve, with a castle which was frequently a royal residence, and a mint. In the early 10th century the remains of Saint Oswald were brought to a small church here and shrine built there, a draw for pilgrims. The core street layout is thought to date to the reign of Æthelflæd in late Saxon times.