A little over 20 years after the fresco by Bicci di Lorenzo, the Florentine Republic decided to build a new circuit of walls for the village of Empoli: an exceptional case, certainly due to reasons of military strategy. The new defensive system, built between 1466 to about 1500, was designed by the most avant-garde military architects of the time, who then worked in service of the Medici, Antonio il Vecchio and Giuliano da Sangallo. The area surrounded by the new walls was slightly larger than that of the 14th century area, but was built according to innovative defensive criteria. In the new layout, the access gates were reduced from six to four, one for each side of the quadrilateral. The two gates on the east and west sides, for entrance and exit of the Via Pisana, were positioned so that the internal road axis between the two doors fell right on the town’s central block. In essence, anyone who entered from the Via Pisana found himself faced, as has been pointed out by more than one observer, by the barrier of the houses of the central block, which had to be skirted, on the right or on the left, in order to make use of the village’s inner streets. Recent analyses of the surviving structures of the original defensive layout of Empoli, such as the circular tower of Santa Brigida, have demonstrated the use of technological and structural solutions on curtain walls, ramparts, or in the type of loopholes characterizing the new military architecture. The mighty walls of the brothers from Sangallo are perfectly recognizable in the very detailed fresco, by Giorgio Vasari, of the hall of Clement VII in Palazzo Vecchio, dated 1555–60, representing Empoli during the siege of 1530. The brick walls with escarpment, terminating in the moat, can be seen, along with the four gates and the square-based corner towers advanced along the line of the walls, as well as the semicircular wall towers on each side. This is the image Leonardo had before his eyes when he depicted the turreted quadrilateral of Empoli on the beautiful bird's eye map of the Windsor Castle Collection RL 12685. In the drawing, the village of Empoli, in its regular layout, it its walls defended with corner towers, is a very short distance from the castle of Pontorme, depicted with the 14th-century walls of a fortified village. The two villages are connected by the thin line of Via Pisana.