The Serraglio are defensive walls which were built by the Scaligers to protect the south-western side of the area. The walls were began in 1345 under Mastino II and completed under Cangrande II in 1355. They stretched for 13 kilometres and contained defensive towers along their length way. They flanked the Tione River between Valeggio sul Mincio and the Gazolo Tower near Nogarole Rocca. The walls were damaged in 1404 by Federico Gonzaga’s soldiers and are now all but lost with a few visible ruins remaining in Villafranca, on the left bank of the Tione River.