one gate, and the Sacellum itself (k) is set against the wall, leaving the central court clear. Bshair is no longer a Roman limes fortress, it is a military caravanserai. The same definition applies to the undated fort at Qasṭal (Fig. 26). Again, the interior buildings are set round the encompassing wall, but they are not single chambers; they are the baits of the Mesopotamian palaces, minus the lîwân. Each unit is composed of a small open court with rooms on either side (this is the normal arrangement, though three of the baits at Qasṭal have rooms upon one side only), and in the interior of the complex a court is left over. There is no room in this scheme for a Praetorium and accordingly it is given a place outside the walls,[202] but fragments of carved ornament found in the principal court make it probable that a small Sacellum occupied the centre. This principle is retained in the caravanserai fortresses of other parts of Syria. At Dair al-Kafh (A.D. 306) a small temple, which was subsequently converted [Illustration: FIG. 26. Qasṭal. (From _Provincia Arabia_, by kind permission of Professor Brünnow.)] into a chapel, stood in the centre of the court;[203] in the barracks at Anderîn (A.D. 558) a chapel is similarly placed,[204] and at Qaṣr ibn Wardân (A.D. 561) a building, the uses of which have not been determined, stands in the barrack yard.[205] Beyond this small resemblance, the divergence of Qasṭal from the Roman camp type is complete. All the more noticeable is its likeness to the only Sasanian castrum of which we have any sufficient record. Qasṭal belongs to the same family as the fort at Qaṣr-i-Shîrîn (Plate 73, Fig. 1). The towered walls, the single gate, the chambers or baits placed round the interior of the walls so as to leave a central court over, all these are characteristic of the older building; but at Qaṣr-i-Shîrîn the lodging of the commandant is placed inside the court, whereas at Qasṭal it is outside.[206] In the Zohâb district there is another building of a somewhat similar type, but it looks more like the ordinary caravanserai than like a fortress.[207]