Castello Aragonese, Ischia

Castello Aragonese, Ischia, is the oldest continuously inhabited fortress in Italy, with origins dating to 474 BC. Perched on a volcanic rock islet, it connects to the mainland via a 220-meter stone bridge built in the 15th century. The site encompasses a cathedral and 200 rooms, with a recorded 150,000 tourists exploring its tunnels annually. This ancient settlement predates every other castle on this list by over 1,500 years, making it historically richer than #5 Rocca Scaligera, Sirmione's 13th-century structure.