Bearing in mind what was the social condition of Rome during the middle ages, it becomes easier to understand the architectural barrenness which at first excites the visitor's surprise. Rome had no temporal sovereign, and there were therefore only two classes who could build at all, the nobles and the clergy. Of these, the former had seldom the wealth, and never the taste, which would have enabled them to construct palaces graceful as the Venetian or massively grand as the Florentine and Genoese. Moreover, the constant practice of domestic war made defence the first object of a house, beauty and convenience the second. The nobility, therefore, either adapted ancient edifices to their purpose or built out of their materials those huge square towers of brick, a few of which still frown over the narrow streets in the older parts of Rome. We may judge of their number from the statement that the senator Brancaleone destroyed one hundred and forty of them. With perhaps no more than one exception, that of the so-called House of Rienzi, these towers are the only domestic buildings in the city older than the middle of the fifteenth century. The vast palaces to which strangers now flock for the sake of the picture galleries they contain, have been most of them erected in the sixteenth or seventeenth centuries, some even later. Among the earliest is that Palazzo Cenci[342], whose gloomy low-browed arch so powerfully affected the imagination of Shelley. [Sidenote: Ambition, weakness, and corruption of the clergy.] It was no want of wealth that hampered the architectural efforts of the clergy, for vast revenues flowed in upon them from every corner of Christendom. A good deal was actually spent upon the erection or repairs of churches and convents, although with a less liberal hand than that of such great Transalpine prelates as Hugh of Lincoln or Conrad of Cologne. But the Popes always needed money for their projects of ambition, and in times when disorder or corruption were at their height the work of building stopped altogether. Thus it was that after the time of the Carolingians scarcely a church was erected until the beginning of the twelfth century, when the reforms of Hildebrand had breathed new zeal into the priesthood. The Babylonish captivity of Avignon, as it was called, with the great schism of the West that followed upon it, was the cause of a second similar intermission, which lasted nearly a century and a half. [Sidenote: Tendency of the Roman builders to adhere to the ancient manner.] [Sidenote: Absence of Gothic in Rome.]