Oxford Castle is an earthwork motte and bailey fortress, founded in 1071 by Robert d'Oilly. Possibly built the foundations of an exisiting Saxon building collegiate Church of St George in the castle, the tower of which served not only as the church belfry, but also as the defence of the western angle of the castle, The summit of the motte has lost its two decagonal shell-walls but retains a hexagonal well-chamber. The plain, St George's tower may have been added to the castle around 1074, using the square four storey St George's Tower is stepped inwards up its height, with a round stair turret set to one corner. A high wall with round-headed opening's guards the roof. 12 miles south-east is Wallingford Castle. The shell keep was added later. The castle was ruinous by 1331. The site was largely cleared and new buildings completed in 1805. Excavations have revealed numerous Saxon pits and traces of habitation under the motte where 10th century pottery was found. A secular college, St George in the Castle, was founded 1074 and absorbed by Osney Abbey 1144. The abbey established a college for scholars as well as chaplains circa 1480. This was dissolved in 1539. The crypt remains, but it has been demolished and reconstructed first in 1794 and again in 1848.