The Great Mosque of Sfax was the most important mosque in the old city of Sfax, Tunisia. It was initially built towards the mid-9th century under the rule of the Aghlabid dynasty, a vassal state of the Abbasid Caliphate. The mosque was the urban and religious heart of the city and it underwent several major modifications in later periods. Architecturally, it is notable for its minaret and its unusually decorated eastern façade.