The Castillo de Santa Catalina rides the ridge above Jaén at 800 metres, with the city tumbling down its eastern flank. The site was first fortified by the Romans, then by the Visigoths, but most of what stands today is the work of the Moorish Banu Said dynasty in the 12th and 13th centuries, with substantial Christian additions after the Reconquista in 1246.
You can walk the battlements, climb the keep for the view (one of the best in Andalusia — a green sea of olive trees rolling to every horizon), and visit the small interpretation centre. The castle is now attached to the Parador de Jaén, one of Spain's state-run hotels, where you can go for a drink even if you are not staying.