The town’s castle, high over town, is an impressive place, a huge medieval complex characterised by two towers. The basic entry includes an audio guide and access to the Torre del Espolón, reconstructed after the earthquake, various cisterns and ramparts as well as exhibition spaces.The handsome Torre Alfonsina and the reconstructed synagogue plus ruins of the Jewish quarter can be visited twice or more daily by recommended guided tour (€4 each). A combined €10 entrance fee includes both tours.
In the castle, there's a central cafe in the old stables as well as a playground area: they generally make a big effort for kids, with weekend and summer actors and activities. The two guided visits are in Spanish. The Torre Alfonsina is included in the audioguide, so you can listen to that while the guide is speaking. The synagogue is not: some guides will summarise in other languages according to need.
The hilltop has been continuously occupied since the Chalcolithic period, but the current fortress has its origins with the Moors, when it was a key strategic asset in the Reconquista battles. After 1492, it fell into disrepair but was remodelled during the Napoleonic wars in the early 19th century.