In various portions of the double ambulatory passage as well as some of the chapels, the fine, deep green and gold and blue Romanesque coloring may still be seen, giving a rich impression of the old barbaric splendor and gem-like richness so befitting the clothing of the style. Other portions, now bare, must surely all have been colored. The delicate, slender shafts, subdividing unequally the ambulatory, have really no carrying office, but were probably introduced to lessen the difficulty of vaulting the irregular compartments of such unequal sides. Gothic art was still in its infancy, and the splendid grasp of the vaulting difficulties and masterly solution of its problems exemplified in so many later ambulatories, had not as yet been reached. Here we have about the first fumbling attempt. The maestro is still fighting in the dark with unequal thrusts, sides and arches of different widths, and a desire to meet them all with something higher and lighter than the old continuous barrel vault. A step forward in the earnest effort toward higher development, such as we find here, deserves admiration. The profiles of the ribs are simple, undecorated and vigorous, as were all the earliest ones; in the chapels, or rather the exedras in the outer walls, the ribs do not meet in a common boss or keystone, its advantages not as yet being known to the builders. A good portion of the old roof-covering of the Cathedral, not only over the eastern end, but pretty generally throughout, has either been altered, or else the present covering conceals the original. Thus it is easy to detect from the outside, if one stands at the northwestern angle of the church and looks down the northern face, that the upper masonry has been carried up by some three feet of brickwork, evidently of later addition, on top of which comes the present covering of terra-cotta tiles. The old roof-covering here of stone tiles, as also above the apse, rested directly on the inside vaults, naturally damaging them by its weight, and not giving full protection against the weather. The French slopes had in some instances been slavishly copied, but the steep roofs requisite in northern cathedrals were soon after abandoned, being unnecessary in the Spanish climate. Over the apse of Avila, there may still be found early thirteenth-century roofing, consisting of large stone flags laid in rows with intermediary grooves and channels, very much according to ancient established Roman and Byzantine traditions. Independent superstructure above the vault proper, to carry the outside covering, had not been introduced when this roofing was laid.