The original windows generally still remain. Those in the aisles are single round-headed lights of grand size, with double engaged shafts, both inside and outside: those in the clerestory are of more advanced character, some being of two and some of four lights, of the best early plate tracery, with pointed enclosing arches. The western bay of the choir has lancet clerestory windows, and the apse of seven sides has also a lancet in each face, with a sort of triforium below, which is now closed, but which before the addition of the procession-path was probably pierced. Below this quasi-triforium the wall of the apse is circular in plan, whilst above it is polygonal, and the difference shows the very gradual way in which the building was erected, one of the most usual points of distinction between the Romanesque and the early-pointed planning of an apse being that in the former it is circular, and in the latter polygonal. In speaking of the windows, I have omitted to mention the finest, which are undoubtedly the roses in the principal gables. That in the south transept is one of the finest I know;[198] and whilst it is remarkable for the vigorous character of its design it is also to be noted for a peculiarity which I have before observed in early Spanish traceries. This is the mode in which the traceries are, as it were, packed against each other. It is especially noticeable in the outer line of circles which are inserted like so many wheels abutting against each other, and without the continuous central moulding to which we are generally accustomed. Here, as well as in the interior, the dog-tooth ornament is freely used; and the outer mouldings of the circle are of good character. The exterior of this church is of as great interest as the interior. The two western steeples are of the very plainest possible character, pierced merely with narrow slits, which light the small chambers in the interior of the tower. The buttresses are of enormous size; and in the angles between them and the walls are set engaged shafts, which run up to and finish under the arcaded eaves-cornices with which the walls are finished under the roof. At the west end these shafts are carried up to a greater height, and support three bold arches, one in each division of the façade, corresponding in height pretty nearly with the groining inside. I find, on looking at my notes on this church, that I observed upon this as a feature which I recollected at Notre Dame, Poitiers; and there is some significance, therefore, in the record of the fact that the second bishop, in whose time probably this part of the church was built, was a native of that city.