It cannot be denied that the two cathedrals in question bear a strong resemblance to one another. Nevertheless, their plan of construction is far from being identical. Both have the form of a Latin cross, but St. Sernin has five naves, Santiago only three. The proportions of the Spanish edifice are more harmonious than are those of the French one. The naves of St. Sernin are too long in proportion to the length of her transept. The transepts of the two cathedrals are very much alike; each has one wide central nave, and a surrounding collateral one. St. Sernin has two small apse-chapels opening on the southern side of each arm of the transept, and Santiago must have originally had the same, though only one exists to-day. The principal nave in each case is headed by a semicircular apse fringed with five apse chapels. Fernandez Casanova, after careful and minute study of both edifices, has pointed out two other radical differences, beside that of the number of naves, and the disproportionately long naves of St. Sernin. Firstly, the cathedral of Santiago has its two lofty central naves entirely surrounded by a collateral one without any interruption, whereas that of St. Sernin has two distinct collateral naves on either side of the principal nave; but these verge into one on reaching the transept, with a result that is far less symmetrical: secondly, the spaces into which the collateral naves of St. Sernin are divided are square, while in the case of Santiago cathedral they are rectangular. Then, too, the towers of Santiago are placed to the north and south of the west front, not to the west of it, as is the case with that of St. Sernin. Besides, according to the description given by Americus in the Codex of Calixtus II., the cathedral of Santiago could originally boast of no less than nine towers, and traces of some of them are still discernible in spite of the countless alterations and mutilations to which the building has fallen a victim. In the construction of the triforium galleries of these respective cathedrals there is also a notable difference: in that of Santiago one uninterrupted gallery runs round the whole edifice. Ascending by the broad tower staircase, I was able to pass round the inner side of the outer walls of the entire building. The galleries of St. Sernin only surround the body of the church. Both cathedrals have their central naves covered with barrel vaults,[130] and their side naves with quadripartite ones. Beside the differences I have pointed out, there are also many minor ones, which will be found conscientiously described by Fernandez Casanova.