Outa el Hammam, the central square, is dominated by the 15th-century kasbah, now the Musée de Chefchaouen, and the town's Grand Mosque. The kasbah was constructed by Morocco's greatest builder, Sultan Moulay Ismail. As a prison it housed the leader of the 1920s Riffian revolt, Abd al-Karim. The museum has an exhibition of local dress, musical instruments, pottery, weapons, and a collection of photos depicting place Outa el Hammam and the kasbah in the 1920s. It's worth climbing to the top for a sweeping view of the town, as well as a look at the dungeons and prison cells below. There's also a quiet Andalusian garden in which to relax, and an art gallery often housing temporary art exhibitions.

Next door is the Grand Mosque -- currently receiving a much-needed exterior makeover -- with its unusual octagonal minaret.