Once acting as a barrage to the Alps and now a World Heritage property, the three impressive castles of Bellinzona are among the most significant examples of medieval military architecture. They were built by the Dukes of Milan to bar the route southwards to the Swiss. Bellinzona occupied a strategic position between north and south back then too. Over the course of the centuries, the three castles of Castelgrande, Montebello and Sasso Corbaro have been reconstructed and restored many times. With its walls, towers, battlements and gates, this impressive defensive complex remains a source of wonder to those who view it today.