The history of English medieval architecture is so well explored a subject that it is easy to forget how much we do not know about the buildings of medieval England. What survives is only a part of what once existed, and the accepted story might be materially different if (to give only three examples) Winchcombe Abbey had been preserved instead of Gloucester, Oseney instead of St. Frideswide's, Oxford, Nottingham Castle instead of Windsor. We shall never know whether the surviving sample is truly representative, and there are many problems in the history of English Gothic whose solutions lie buried in the ruins of our dissolved abbeys and demolished palaces. Chief among the latter was the palace of Westminster, for five centuries the principal residence of cur medieval kings and the centre of their government. All that now remains of its many and often magnificent buildings are the great hall, the crypt of St. Stephen's Chapel, and the Jewel Tower, the last now admirably restored and displayed by the Ancient Monuments Department of the Ministry of Works.