Roman city life and culture changed greatly in the early Middle Ages. Although Italian cities remained inhabited, they contracted significantly in size. Rome, for instance, shrank from a population of hundreds of thousands to around 30,000 by the end of the 6th century. Roman temples were converted into Christian churches and city walls remained in use. In Northern Europe, cities also shrank, while civic monuments and other public buildings were raided for building materials. The establishment of new kingdoms often meant some growth for the towns chosen as capitals. Although there had been Jewish communities in many Roman cities, the Jews suffered periods of persecution after the conversion of the empire to Christianity. Officially they were tolerated, if subject to conversion efforts, and at times were even encouraged to settle in new areas.
Try to answer this question if possible (otherwise reply "unanswerable"): What new use was found for Roman temples?
Christian churches