Although the mosque is known to have been founded at the end of the 7th or start of the 8th century CE, its current architectural form dates from a reconstruction in the 9th century CE, including many antique columns reused from ancient Carthage, and from later additions and restorations over the centuries.

The mosque hosted one of the first and greatest universities in the history of Islam, like that of University of Fatima al-Fihri. Many Muslim scholars graduated from al-Zaytuna for over a thousand years. Ibn 'Arafa, a major scholar of the Maliki school, al-Maziri, the great traditionalist and jurist, and Aboul-Qacem Echebbi, a famous Tunisian poet, all taught there, among others.

The "Mosque of Olive" derives its name from various legends. One claims it was built on a site marked by an olive tree, while another, recorded by historian Ibn Abi Dinar, links it to a Byzantine church dedicated to Santa Olivia. Excavations in 1969–1970 uncovered Byzantine-era structures, possibly a basilica or fortification, repurposed for the mosque. Santa Olivia remains culturally significant in Tunisia. A legend warns that recovering her relics would herald the end of Islam, a belief echoed in 1402 CE when Sicily's King Martin I unsuccessfully requested the relics from Ifriqiya's ruler, Abu Faris Abd al-Aziz II, a member of the Hafsid dynasty. This veneration persists, symbolizing the intertwined heritage of the site.

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Founding and Early Period
The origins of al-Zaytuna Mosque are shrouded in differing historical accounts. While Ibn Khaldun and Al-Bakri attribute its founding to Ubayd Allah ibn al-Habhab in 114 Hijri (circa 731 CE), alternative sources suggest that Hasan ibn al-Nu'man, who conquered Tunis and Carthage, established it in 79 Hijri (circa 698 CE) or 84 Hijri (703 CE). Modern scholarship leans toward the earlier date, asserting that the mosque was initially constructed by Ibn al-Nu'man soon after the conquest of Tunis, later expanded by Ibn al-Habhab. This interpretation is supported by the improbability of a significant settlement like Tunis lacking a mosque for decades after its conquest.

Aghlabid Period
The mosque's most significant reconstruction occurred under the Aghlabids in the 9th century. Completed in 864–865 CE, this transformation underlined the influence of Abbasid patrons, with an inscription crediting Caliph Al-Musta'in Billah, overseer Nusayr, and architect Fath al-Banna'. The Aghlabid design mirrored that of the Mosque of Uqba in Kairouan, emphasizing monumental architecture and grandeur. However, later modifications obscured much of the original structure, save for elements like the prayer hall's interior and certain bastions. Notably, the absence of a minaret at this time indicates either architectural preference or theological hesitation regarding its inclusion.

Zirid Period
The Zirid dynasty, ruling in the late 10th century as Fatimid clients, added significant elements to the mosque between 990 and 995 CE. This included galleries around the courtyard and the iconic Qubbat al-Bahu dome, completed in 991 CE. Inscriptions from this era, despite later erasure of patrons' names, hint at the craftsmanship of figures like Ahmad al-Burjini and Abdallah ibn Qaffas. These additions reflect the continued emphasis on embellishing the mosque's aesthetic and functional aspects.

Hafsid Golden Age
Under the Hafsids (13th–15th centuries), Al-Zaytuna gained prominence as Tunis became Ifriqiya's capital, surpassing Kairouan's Mosque of Uqba in prestige. Hafsid rulers such as Al-Mustansir (1250 CE) and Abu Yahya Zakariya undertook significant restoration efforts, adding ablution facilities and the mosque's first documented minaret in 1438–1439 CE. The minaret, though later replaced, marked the mosque's evolving architectural profile.

Ottoman and Modern Period
The mosque endured turbulence during the Spanish occupation of 1534, losing many manuscripts and treasures. Under Ottoman rule, both the Muradid and Husaynid dynasties restored its structures and institutions, maintaining its stature as a center of Islamic learning. Notable additions include a loggia in 1637 and the minaret's 1894 reconstruction in the Almohad style. The 20th century saw extensive restorations under Presidents Bourguiba and Ben Ali, ensuring its preservation as a symbol of Tunisia's Islamic and cultural heritage.

The al-Zaytuna Mosque's architectural evolution and historical significance encapsulate the interplay of conquest, patronage, and religious devotion across centuries, cementing its status as a beacon of Islamic civilization in North Africa.

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Design and Layout
The al-Zaytuna Mosque draws heavily on the architectural principles of earlier Islamic structures, particularly the Mosque of Uqba in Kairouan, completed decades earlier. Its design combines a trapezoidal courtyard (sahn) and a hypostyle prayer hall. Despite its irregular layout, where lines are not perfectly parallel or perpendicular, this is imperceptible to visitors. Unlike its Kairouan counterpart, the al-Zaytuna Mosque's minaret was a later addition. Integrated seamlessly into the surrounding urban fabric, most of its exterior remains obscured by adjacent buildings, with the exception of the eastern façade, which features a 17th-century arcaded loggia.

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Courtyard (Sahn)
The mosque's courtyard, accessible via seven doorways, is encircled by galleries supported by arcades of arches and columns. These galleries vary in age, with the southern gallery, dating back to the 10th-century Zirid restoration, showcasing antique spoliated columns and capitals. The remaining galleries were reconstructed in the 17th and 19th centuries, with imported Italian columns added in the mid-19th century. The courtyard's pavement consists of antique marble plaques, further emphasizing the use of spolia in its construction.

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Minaret
The minaret, positioned in the courtyard's northwest corner, rises to a height of 43 meters (141 feet) and was constructed in 1894. Its design echoes the Almohad style, seen in the Kasbah Mosque of Tunis, with decorative limestone strapwork in a sebka pattern on an ochre sandstone background. This later addition integrates seamlessly into the mosque's aesthetic while marking its evolution over centuries.

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Central Dome (Qubbat al-Bahu)
Dominating the entrance to the prayer hall is the Qubbat al-Bahu, a dome added during the Zirid period around 991 CE. Measuring approximately 12 meters in height and 4 meters in width, the dome is lauded as a masterwork of western Islamic architecture. Its ribbed construction rests on an octagonal base, transitioning into a square foundation. Ornamentation includes intricate moldings, blind arches, pilasters, and polychrome stonework in red, white, and black. Fatimid floriated Kufic inscriptions embellish its base, reflecting the artistic and theological influences of the era.

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Prayer Hall
The hypostyle prayer hall features 15 aisles divided by rows of columns supporting horseshoe arches, with the central aisle, leading to the mihrab, being wider. A transverse aisle also runs parallel to the qibla wall. Most of the hall's approximately 160 columns are antique spolia, likely sourced from Carthage. The dome above the mihrab, dating to the Aghlabid period (9th century), preserves Kufic inscriptions from the same era.

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Mihrab and Minbar
The mihrab, extensively redecorated over centuries, retains its Aghlabid foundation, including a marble plaque adorned with gold leaf and Kufic inscriptions. Surrounding stucco decorations primarily date to the 17th century, with some panels from the Aghlabid period still visible. Adjacent to the mihrab, the wooden minbar is one of the oldest after that of Kairouan. While its structure has undergone significant renovations, original Aghlabid panels remain, complemented by Ottoman additions from 1583.