Their towers seem to have been of two forms, ecclesiastic and civil. The ecclesiastical bell-tower, square with a straight unbroken line, with neither buttress nor projection till the summit, where the bracket-supported arches expand like a flower. Sometimes each storey had a string course, with smaller arches beneath it, as in the tower at Prato. The windows, too, as we have said, had a fixed rule; they are smaller below, and grow larger and more airy as they ascend. You go up from a mere orifice on the first floor to a one-arched window on the second, a two-arched on the third, to a three or even four-arched one near the summit. The characteristics of civil towers at this time were their solidity as a means of defence, and their height as a means of vigilance; they appear to be chiefly circular, offering no corners, but a curved surface from which missiles could easily glance off. The windows were narrow outside, expanding wider within. If there were a double-light window, it would be on the very high storeys, out of arrow aim. Nearly all the ancient fortresses have round towers, but I know of very few church towers that are so, except the one at Classe near Ravenna. Before the thirteenth century, neither brackets nor projecting cornices were used, and the tower rose in a single straight line from base to battlement, so that projectiles fell straight down. It was later that architects discovered the value of the projecting _baluardo_. As to battlements, these too came from the antique; Babylon and Nineveh show proofs of them, and Homer speaks of the battlemented towers of Asia and Greece. Muratori[54] derives the Italian term _merlo_, from _mirare_ (to take aim), the battlements being made for the shelter of the archers, and their convenience in shooting. When fire-arms came in, the need of battlemented towers ceased. The principal Longobardic military towers remaining to our day, are, the tower of the ruined fortress of Baradello, which dominates the road to Camerlata, and the towers, now mutilated, in the wall of Como, one of which, erected on arches, forms the gate of the city towards Camerlata.