The claim that it was the Arab commander Maslama who had requested the construction of the first mosque in Constantinople cannot be allowed to stand. It seems to have developed from a claim that the emperor Leo III (717-41) had allowed him entry into Constantinople in 718, which claim had started as part of a work in praise of Leo, but which had then been turned against him by later redactors. The fact that there is no good, contemporary evidence as to who built the first mosque in Constantinople suggests that no-one did as such. The absence of such evidence points to a policy of quiet tolerance and goodwill on the part of successive imperial courts so that they allowed the gradual conversion of part of the quarters assigned to Muslim prisoners into a mosque. When controversy over the existence of this mosque finally developed, popular speculation blamed its construction on the iconoclast emperor, Leo, and the story of the second siege of Constantinople was re-written accordingly. As to the date of this controversy, it may well have occurred as early as c. 813 following the desecration of the churches in Jerusalem at that time.