A consideration of one, without something more than mere mention of the other, is not possible, and incidentally--even for the church-lover--nothing can be more interesting than the great works of fortification--strong, frowning, and massive--as are yet to be seen at Béziers, Carcassonne, or Avignon. It was this latter city which sheltered within its outer walls that monumental reminder of the papal power which existed in this French capital of the "Church of Rome"--as it must still be called--in the fourteenth century. To the stranger within the gates the unconscious resemblance between a castellated and battlemented feudal stronghold and the many churches,--and even certain cathedrals, as at Albi, Béziers, or Agde,--which were not unlike in their outline, will present some confusion of ideas. Between a crenelated battlement or the machicolations of a city wall, as at Avignon; or of a hôtel de ville, as at Narbonne; or the same detail surmounting an episcopal residence, as at Albi, which is a veritable _donjon_; or the Palais des Papes, is not a difference even of degree. It is the same thing in each case. In one instance, however, it may have been purely for defence, and in the other used as a decorative accessory; in the latter case it was no less useful when occasion required. This feature throughout the south of France is far more common than in the north, and is bound to be strongly remarked. Two great groups or divisions of architectural style are discernible throughout the south, even by the most casual of observers. One is the Provençal variety, which clings somewhat closely to the lower valley of the Rhône; and the other, the Aquitanian (with possibly the more restricted Auvergnian). These types possess in common the one distinctive trait, in some form or other, of the round-arched vaulting of Roman tradition. It is hardly more than a reminiscence, however, and while not in any way resembling the northern Gothic, at least in the Aquitanian species, hovers on the borderland between the sunny south and the more frigid north. The Provençal type more nearly approximates the older Roman, and, significantly, it has--with less interpolation of modern ideas--endured the longest. The Aquitanian style of the cathedrals at Périgueux and Angoulême, to specialize but two, is supposed to--and it does truly--bridge the gulf between the round-arched style which is _not_ Roman and the more brilliant and graceful type of Gothic. With this manner of construction goes, of course, a somewhat different interior arrangement than that seen in the north. A profound acquaintance with the subject will show that it bears a certain resemblance to the disposition of parts in an Eastern mosque, and to the earlier form of Christian church--the basilica. In this regard Fergusson makes the statement without reservation that the Eglise de Souillac more nearly resembles the Cairène type of Mohammedan mosque than it does a Christian church--of any era.