Though the displays aren't especially exciting, a visit to this little museum does provide some context and perspective on the culture of the island, one you're unlikely to get at the beaches of Sidi Mahares. It houses a good collection of local costumes as well as pottery and jewellery though exhibits are only labelled in Arabic and French. The room housing the latter still has the original terracotta domed tile ceiling as well as superbly intricate latticework design around the base.
Indeed, the building itself is as interesting as the exhibits, with courtyards, arches and underground workshops. The museum occupies the Zaouia of Sidi Zitouni under the eucalyptus trees about 200m from the town centre; look for the ticket office in the small traditional weaver's hut near the entrance.