This forbidding castle guards the northern Sierra Nevada from a hilltop looming over the sleepy village of La Calahorra, 16km southeast of Guadix. Built between 1509 and 1512, on the ruins of a Moorish fortress, its four cylindrical towers and blank outer wall enclose a lavish Renaissance interior, with an elegant courtyard and a staircase of Italian Carrara marble. Visits are by 30-minute guided tour (in Spanish and, sometimes, English).
The interior was built at the behest of Rodrigo Díaz de Vivar y Mendoza, Marqués de Zenete, the aristocrat commander of the surrounding plains, whose tempestuous love life included a spell in Italy unsuccessfully wooing Lucrezia Borgia. The castle was later abandoned for several centuries.
The castle is up a rocky track, so you might prefer to park in town and walk up the footpath from just north of Plaza del Ayuntamiento.