This was well-worth the visit!  The castle itself is about 2500 years old and has had numerous inhabitants including peasants, royalty, nuns, and prisoners, to name a few. It was an easy walk from our hotel with a great view of the castle from the beach and a nice walk across the bridge which connects it to the mainland.  The views from the top of the castle are stunning and you can see 360* around providing opportunities for amazing pictures. On clear days you can easily see Capri and Mt. Vesuvius. One of the most interesting (creepy) things is the crypt where the nuns decomposed after their death. They sat on toilet-like seats and there were bowls underneath to catch their bodily fluids. There was also a torture museum with some very graphic pictures and archaic sexual instruments.  If you are in Ischia, Castello Aragonese is a must see for sure!