During the first three centuries the Christian religion was discredited and persecuted; and though many interesting memorials of this time (some of them having an indirect bearing upon architectural questions) remain in the Catacombs, it is chiefly for their paintings that the touching records of the past which have been preserved to us in these secluded excavations should be studied. Early in the fourth century Constantine the Great became Emperor, and in the course of his reign (from A.D. 312 to 337) he recognised Christianity, and made it the religion of the State. It then, of course, became requisite to provide places of public worship. Probably the Christians would have been, in many cases, reluctant to make use of heathen temples, and few temples, if any, were adapted to the assembling of a large congregation. But the large halls of the baths and the basilicas were free from associations of an objectionable character, and well fitted for large assemblages of worshippers. These and other such places were accordingly, in the first instance, employed as Christian churches. The basilica, however, became the model which, at least in Italy, was followed, to the exclusion of all others, when new buildings were erected for the purpose of Christian worship; and during the fourth century, and several succeeding ones, the churches of the West were all of the basilica type. What occurred at Constantinople, the seat of the Eastern Empire and the centre of the Eastern Church, will be considered presently. There is probably no basilica actually standing which was built during the reign of Constantine, or near his time; but there are several basilica churches in Rome, such as that of San Clemente, which were founded near his time, and which, though they have been partially or wholly rebuilt, exhibit what is believed to be the ancient disposition without modification. [Illustration: FIG. 156.--INTERIOR OF A BASILICA AT POMPEII. _Restored, from descriptions by various authors._]