The Castello di San Giorgio is a moated rectangular castle in Mantua. Each of its four corners has a large tower and the moat is crossed by three drawbridges.
It was built between 1395 and 1406 on the ruins of the church of Santa Maria di Capo di Bove for Francesco I Gonzaga, to designs by Bartolino da Novara. Ludovico III Gonzaga gave over his rooms in the "Corte Vecchi" to pope Pius II for the Council of Mantua in 1459 - that year, he commissioned Luca Fancelli to rebuild the castle as a palazzo rather than as a defensible castle. He also commissioned the frescoes of the castle's Camera degli Sposi. In 1490 the castle became the site of the studiolo of Isabella d'Este, remaining there until she moved it to the "Corte Vecchi" in 1519-1522. In 1496 the condottiero Paolo Vitelli was captured by Francesco II and imprisoned in the castle. It remained the main Gonzaga residence for around a century until Guglielmo Gonzaga moved his apartments to the rebuilt "Corte Vecchi".
In 1810 the Tyrolean fighter Andreas Hofer was imprisoned in the castle before his execution by the Kingdom of Italy. Mantua became part of the Austrian Empire in 1814 and from 1815 it was a maximum security prison for the Empire's political opponents, such as the Belfiore martyrs from 1852 onwards. Others pro-Risorgimento figures imprisoned there included Ciro Menotti and Teresa Arrivabene. The building's structure was damaged by the 2012 Emilia earthquake.