There are castles and then there’s Ischia’s Castello Aragonese, a veritable fort-city set on its own craggy islet, looking like a cross between Harry Potter’s Hogwarts and Mont Saint Michel. While Syracusan tyrant Gerone I built the first fortress here in 474 BC, the bulk of the current structure dates from the 1400s, when King Alfonso of Aragon gave the older Angevin fortress a thorough makeover, building the fortified bastions, current causeway and access ramp cut into the rock.
At the base of the complex you pay the entrance fee and then ascend via a lift or a series of paths that take you on a looping route through the buildings and lush gardens. The signposted route starts with the relatively modern and plain Chiesa dell'Immacolata, built in 1737 over an old church. Commissioned by the adjoining Convento delle Clarisse (Convent for Clarisse nuns), it was left in its minimalist state after building funds ran out. Next door, the nuns contributed to the castle's most bizarre and macabre sight. When the erstwhile sisters died, their corpses were taken into the windowless, airless Cimitero delle Monache Clarisse where they were propped up on toilet-like chairs. The living nuns were expected to pray daily to the decomposing corpses as a grim reminder of their own mortality. Not surprisingly, many of them caught diseases in the process, some fatal. The empty chairs remain on view in the cellars as a chilling reminder.
Far brighter are the sunbaked, stuccoed ruins of the 14th-century Cattedrale dell’Assunta, which collapsed under cannon fire in 1809 as the British tried to shell Napoleon's occupying army into submission. The 11th-century crypt below features snippets of 14th-century frescoes inspired by Giotto.
Carry on until you reach the elegant, hexagonal Chiesa di San Pietro a Pantaniello and sombre Carcere Borbonico, the one-time prison for leading figures of the Risorgimento (the 19th-century Italian unification movement), such as Poerio, Pironti, Nusco and Settembrini. There's a small and grisly Museo delle Torture, with a collection of medieval torture instruments and impressive armour and weaponry.
Elsewhere, you can stroll the castle's terraced grounds dipping into various other small chapels and drinking in the views from the Terrazzo degli Ulivi (Olive tree terrace).
The complex includes a couple of attractive terrace cafes (the highest one offers views across to Capri), as well as an hotel.