From Arcos de la Frontera, take the A-383 northeast, following the signs to Algodonales. Once you reach this town, head south at the junction with CA-531 to Zahara de la Sierra, the most perfect of the province's fortified hilltop pueblos. Trip time from Arcos is about 35 minutes, and the distance is 51km (32 miles).
Zahara is in the heart of the Natural Park Sierra de Grazalema, a 50,590-hectare (125,000-acre) park. An important reserve for griffon vultures, among other creatures, the park is studded with pine trees and oak forests. The Parque Natural Information Office (tel. 95-612-31-14; www.zaharadelasierra.es) is at Calle San Juan (the eastern end of main street). Hours are daily from 9am to 2pm and Monday to Saturday from 4 to 7pm. It dispenses information and maps for those who'd like to go for walks in the park. There are five major routes in the park, and for most you'll need to seek permission at the office, which also organizes horseback riding, canoeing, and bike trips.
The white village of Zahara itself zigzags up the foot of a rock topped by a reconstructed castillo. Houses covered in characteristic red tiles huddle up to the ruined castle. Count on a 15- to 20-minute climb to reach what was once a 10th-century Muslim fortress constructed on Roman foundations 511m (1,676 ft.) above sea level.
Zahara was, in fact, so prized by the Moors that the ruler, Abu al'Hasan of Granada, recaptured it in 1481 from the Catholic troops. But with the fall of Granada at the Reconquista, Zahara once again fell into the hands of the Catholic monarchs. You can visit the Moorish castle, which is always open, offering panoramic views of the surrounding countryside.
The cobbled main street, Calle San Juan, links the two most important churches, Iglesia San Juan and Iglesia Santa María de la Mesa. The latter is an 18th-century baroque church worth a look inside if it's open. It displays an impressive retable with a 16th-century image of the Madonna. The best time to be here is in June for the Corpus Christi celebration (annual dates vary). Streets and walls seem to disappear under a mass of flowers and greenery.