With the exception of the late Tilimsân group, the wooden roof of all the above-mentioned mosques, both in Syria and in North Africa, was supported by columns and arches, the columns having invariably been taken from pre-Mohammadan buildings. Probably the earliest extant example of a mosque in which the arches rested on piers is at Ḥarrân, but the building is unfortunately so much ruined that its exact disposition cannot be determined without excavation. The plan, so far as it is apparent, has been given by Dr. Preusser.[413] The central arch in the north façade of the ḥaram alone remains standing. Its width would seem to indicate that here, as at Damascus, the central aisle was broader than the rest. On either side of it there was an arch of much narrower span.[414] None of the other piers can be placed with certainty. There are some fragments of columns both in the ḥaram and in the east riwâq. An inscription on the east gate gives the name of Ṣalâḥ al-Dîn,[415] but I think it certain that it alludes not to the foundation, but to the restoration of the mosque. The cusped ornament round the relieving arch over the door corresponds with the cusped motive on the façade of the Mayâfârqîn mosque, and the gateway at Ḥarrân has every appearance of being the work of Ṣalâḥ al-Dîn. But the engaged capitals of the interior responds in the east wall, and the wreathed acanthus capital under the central arch of the ḥaram (one capital only is preserved) must be dated several centuries earlier. I do not doubt that they were executed for the places which they occupy, and I agree with Dr. Herzfeld in assigning them to the Umayyad period.[416] I observed, however, among the ruins in the interior of the mosque many fragments of carved ornament which cannot be earlier than the time of Ṣalâḥ al-Dîn, and I came to the conclusion that until the building has received further study it is impossible to make a more precise statement concerning it than that it seems to be a structure of which parts at least belong to the early eighth century, that it had a wide central aisle and four gable roofs supported on masonry piers, or possibly upon piers and columns.