Shirburn castle probably consisted of a quadrangle, enclosed by four ranges of buildings, with a round tower at each corner, and a gate tower in the middle of the west side. The living quarters would have been contained in the four ranges round the quadrangle; one might expect the hall to have been on the east side, opposite the gate tower (as at Bodiam and Lumley). Of the original building there survive the gate tower, the west outer wall, the south outer wall (now englobed in later buildings), and probably the southwest and south-east towers; the other two towers may have been rebuilt at the time of the extensive alterations in C18. Originally there were three drawbridges with a portcullis at the main entrance. The wide moat, doubly wide on one side, is of running water supplied from springs on the east side of the castle and also in the moat itself. In C16 Leland described the building as a 'strong pile or castlelet'. Sir Adrian Fortescue was often there after he left Stonor, and an inventory of his goods at the castle made in February 1539, a few months before his execution, throws some light on the internal arrangement of the rooms at this period. It mentions the wardrobe, the entry, the great chamber at the lower end of the hall, the inner chamber, 'the brusshynge howse', the hall and the chamber over the parlour, and an inner chamber there; there was also a cellar, buttery, chambers each for the butler, priest, horse-keeper, cook, and chamberlains, an additional chamber, a low parlour, a kitchen larder, boulting house, fish-house, garner, brew-house, and other outhouses. From the end of C15, when Richard Chamberlain, his wife, and chaplain died there, to the middle of C17 the castle was lived in, at least for a part of the year by the Chamberlains, and they held it for the king during the Civil War. The importance and size of the building may be judged from the fact that in the 1660's it was among the eleven houses in the county for which 30 hearths or more were returned for the hearth tax of 1665. Only the Earl of Lindsey at Rycote, the Earl of Downe at Wroxton, the Earl of Clarendon at Cornbury, Sir Francis Lee at Ditchley, Sir John Lenthall at Burford Priory, and William Knollys of Rotherfield Greys returned more than Shirburn's 32 hearths. Michael Burghers depicts the castle on his map of the county and the coat of arms of Lord Abergavenny, then lord of the manor, heads the 143 shields drawn in the border. (VCH)