The first care of the Greeks was to build a series of fortresses to hold in check the tribes of mountain and desert which for generations had been acquiring greater boldness in war and pillage. Remains of such forts are all over the country. There is one at Timgad, situate about 150 yards from the Southern Baths. It is a great quadrilateral flanked with square towers, and covering more than 7000 square yards. It is extraordinarily solid in construction, the walls being nine feet thick. But it is at Tebessa that the most perfect example of Byzantine fortification exists. The enceinte encloses the Arab town, and to put it into a state of defence the French have only had to execute a few repairs. For these hastily constructed fortresses any materials which came to hand were used. Into the solid walls faced with square blocks were thrown the debris of private houses, the friezes of temples, the statues of the gods. What the Vandal had spared, the Berber and the Byzantine between them made an end of. Under the shelter of these fortified places a neo-Roman civilization budded again. The great proprietors and the wealthy financiers of the later Empire had disappeared. Their place was taken by the Church. The bishops occupied themselves with business of every description, political, financial, administrative, and even military. Vast sums were spent in the construction of great basilicas and monasteries, the ruins of which may be seen at Timgad and Tebessa to-day. To this period doubtless belongs the huge building, basilica and monastery, to the west of Timgad. It covers a space of not less than 20,000 square yards. The basilica is 200 feet long and 70 feet wide, and is preceded by a court-yard of the same size as itself. It is built chiefly of stones taken from the neighbouring pagan temples, which must have been already in ruin at the time of its erection. If, as some suppose, these great churches were built originally during the fourth and fifth centuries, before the Vandal invasion, there can be little doubt that they were rebuilt with modifications and enlargements during the Byzantine period. The domination of the Church did not make for the prosperity or security of the people. The great dreams of Justinian were never realized; his enterprise from the very beginning had in it the seeds of decay. The rapacity of the ecclesiastics at least equalled that of the former Treasury officials; the husbandmen were plunged in a condition of abject poverty; the persecution of schismatics decimated the population. Native insurrections, mutinies of troops, sullen detestation of the people prepared the way for the easy fall of the Byzantine administration before the invading Arabs of the next century.