The cloister on the south side is almost all modernized, though one or two old doorways remain. That into the south transept has spiral shafts, with the spiral lines reversed at regular intervals. It has also some very good carving of foliage, with birds and naked figures, and on its jambs are some memorial inscriptions of A.D. 1190, 1192, and 1194. On the south side of the cloister is a richly decorated little chapel, which retains in one corner a very curious mediæval organ, with shutters. On the east side and close to the transept, what was no doubt the original Chapter-house still remains, though it is now called the Mozarabic chapel, and was formerly used for the Mozarabic ritual. At present the boy who had the keys said it was not used; but the proper books were all there. It is a very remarkable chamber, square in plan below, and brought to an octagon above by arches thrown across the angles, and finally roofed with a sort of dome, carried upon moulded and carved ribs of very intricate contrivance. The interlacing of these ribs gives the work somewhat the effect of being Moorish, and there can be little doubt, I think, that it owes its peculiarities in some degree to Moorish influence. It will be seen by reference to the plan, that the groining ribs are arranged in parallel pairs. The ribs go from the angles to the centre of the opposite side instead of from angle to angle, and the sixteen ribs form a star-shaped compartment in the centre. This coupling of ribs in parallel lines is a feature of Moorish work, and is seen in the curious mosque, the Cristo de la Luz, at Toledo, and in the somewhat Moorish vault of the Templars’ church at Segovia. But whether Moorish or not, it is a remarkable room, and deserves careful study. The diameter is but a little over twenty-six feet, and the light is admitted by small windows in the upper stage. I should be inclined to attribute this room and its vault to the architect of the lantern of the church, and I regret that the only part of the outside which I could see was so modernized as to render it impossible to ascertain the original design. I call this the Chapter-house, because I find that it opened originally into the cloister, with three arches, that in the centre a doorway, the others windows of two lights--the almost invariable arrangement of all Chapter-houses at this time.[95] A considerable number of masons’ marks remain on the exterior of the early part of this church; and if they are the marks of the men who erected so complicated a piece of stonework as the vault of the Chapter-house, they well deserve to be preserved. Throughout this church, indeed, the masonry is unusually good, and, owing to the rich warm colour of the stone, the eastern apses, though they follow the common design of most of the Romanesque apses in this part of Spain, are more than usually good in their effect.