Dominating the island from a height of over 400 meters above sea level, the medieval village of Giglio Castello appears as a small fortified town, surrounded by an imposing belt of walls along which stand ten towers – seven of them rectangular, three circular – entered through an intricate system of gates and avant-corps. Erected by the Pisans during the 12th century, the town passed in the following centuries under the government of the Medici, who reinforced its defensive system, repeatedly attacked by Saracen pirates. Along the narrow streets, distinguished by arches and "balzuoli" (outside stairways giving access to the upper floors of the houses), it is still possible to admire many of the ancient structures created by the military and civil engineering of over five centuries of history. Remarkable for their historical-scientific interest are the grandiose twelfth-century Rocca Aldobrandesca, the circle of walls with its towers and narrow sentry rounds, and lastly, the cistern built at the order of Ferdinand III after the last Saracen raid, courageously repelled by the inhabitants of Giglio in 1799.