This minaret, the oldest conserved in the Maghreb, stands in the middle of the north portico of the courtyard. Geographer Al-Bakri attributed its construction to the reign of the Umayyad caliph Hicham Ibn ‘Abd al-Malik (r. 724-743), but most archaeologists are convinced it is the work of Ziyadat Allah 1st (r. 817-838). This is corroborated by the fact that the current entrance to the minaret is level with the rest of the mosque of Ziyadat Allah, and that digs conducted at the base of the minaret not having revealed the existence of any previous structure, any raising of the courtyard is thus excluded.
The current minaret, a massive structure with a square base, is made up of three storeys of decreasing size. The first storey, 18.90 meters tall and 10.70 meters wide, tapers from the base to the top by about 50 cm. It is surmounted by rounded merlons, in use in Ifriqiya since Antiquity, attested as early Assyrian architecture. The first courses (stone blocks taken from Antique monuments) are followed by walls of carefully fitted hewn rubble stone, pierced on the courtyard side by three windows and a door (1.85 meters tall, 1 meter wide, with a lintel and abutments made of sculpted marble from the Roman period) surmounted by a horseshoe relieving arch. The second storey, 5 meters tall and 7.65 meters wide, is adorned on each of its four sides with three flat-back niches surmounted by a horseshow arches. The third storey, probably remodelled during the Hafsid period (1228-1574), is made up of a lantern 5.45 meters tall topped with a ribbed dome on squinches. Inside, covered by a barrel vault, a stairway with 129 steps winding around a central pillar leads to the terraces and first storey. While the courtyard façade is pierced with windows to let in light and air, the others have murder holes, which confirms the military role assigned to the minaret, besides its usual function as a tower used for issuing the prayer call.
Most authors establish a parallel between this minaret and the Umayyad minarets of Syria, of which the oldest, those of the Great Mosque of Damascus, rested on the square Roman towers of the temenos of the Temple of Jupiter. There is also a parallel with the Great Mosque of Cordova, built during the era of Hisham 1st at the beginning of the ninth century, and rebuilt in the sixteenth century after an earthquake. Its shape brings to mind the tower of Sheikh ‘Ali Qâsim, near Hama, both of the eighth century. Nevertheless, this tower presents strong analogies with certain Roman lighthouses, as attests the representation of the lighthouse of the port of Selectum in a mosaic found at Ostie, conserved in situ.
The minaret of Kairouan, the tallest in the Maghreb before the construction of the minaret of Kutubiyya in Marrakesh (twelfth century), may be considered as the prototype for the minarets of Occidental Islam, which remained the most popular until the Ottoman period, even though cylindrical minarets appeared at the same time, at the ribât of Monastir and Sousse, and at al-‘Abbassiyya, first Aghlabid capital, in 901. It served as a model, for example, for the minarets of Sfax (tenth century), Tlemcen (1136), and Seville (end of the twelfth century). Some even imitated the choice of the axial position, in the north wall of the enclosure.
Even though the minaret of Kairouan appears austere and adorned with less-sophisticated ornamentation than that of the other Maghrebin minarets, it stands out by its harmonious appearance and striking majesty, which makes a powerful and mysterious impression.
It was in one of the rooms adjacent to this minaret that was discovered a whole treasure of ancient bindings, Qurans and Quranic pages (ninth-thirteenth centuries), treatises on Maliki jurisprudence, and various historical documents pertaining to the city of Kairouan.
 See for example the minaret of the Great Mosque of Tlemcen, Algeria, 1136
 It is worth mentioning in particular the fragmentary Quran, commissioned by Emir Bâdîs ibn al-Mansûr in 1020 for his wet-nurse, written, illuminated and bound by the calligrapher ‘Ali ibn Ahmad al-Warraq.
Golvin, L., Essai sur l’architecture religieuse musulmane, t. III, Paris, 1974, Klincksieck, p. 192-198.
Golvin, L., Essai sur l’architecture religieuse musulmane, t. I, Paris, 1970, Klincksieck.