Al-Zaytuna Mosque

Al-Zaytuna Mosque, also known as Ez-Zitouna Mosque, and El-Zituna Mosque (, literally meaning "the Mosque of Olive"), is a major mosque at the center of the Medina of Tunis in Tunis, Tunisia.
The mosque is the oldest in the Capital of Tunisia and covers an area of with nine entrances.
It has 160 authentic columns brought originally from the ruins of the old city of Carthage. The mosque is known to host one of the first and greatest universities in the history of Islam. Many Muslim scholars were graduated from the Al-Zaytuna for over a thousand years. From Ibn 'Arafa, one of the greatest scholars of Islam, Imam Maziri, the great traditionalist and jurist to the famous Tunisian poet Aboul-Qacem Echebbi and countless others all taught there.
Etymology.
One legend states that it was called "Mosque of Olive" because it was built on an ancient place of worship where there was an olive. However the most accepted explanation is that transmitted by the 17th century Tunisian historian , who spoke about the presence of the tomb of Santa Olivia at that location. Recent research has shown that indeed this mosque was built on a Christian basilica. With the advent of Islam, the church was converted into a mosque, retaining the dedication, but translating the name into Arabic.
The saint is particularly venerated in Tunisia because it is superstitiously thought that if the site and its memory are profaned then a misfortune will happen; this includes a belief that when her relics are recovered Islam will end. This ancillary legend related to the discovery of the saint's relics is widespread in Sicily, however it is connected to other Saints as well.
In 1402 king Martin I of Sicily requested the return of Saint Olivia's relics from the Berber Caliph of Ifriqiya Abu Faris Abd al-Aziz II, who refused him. Even today the Tunisians, who still venerate her, believe that the dominion of their religion will fade when the body of the Virgin Olivia will disappear.
History.
Ez-Zituna was the second mosque to be built in Ifriqiya and the Maghreb region after the Mosque of Uqba in Kairouan. The exact date of building varies according to source. Ibn Khaldun and El-Bakri wrote that it was built in 116 Hijri (731 C.E.) by Ubayd Allah ibn al-Habhab.
A second source states that the Umayyad Hisham ibn Abd al-Malik ordered the building; however, Ahmed In Abu Diyaf and Ibn Abi Dinar attributed the order to Hasan ibn al-Nu'man who led the conquest of Tunis and Carthage, and used it as a place of prayer. Most scholars agree that the third possibility is the strongest by evidence as it is unlikely that the city of Tunis remained a long time without a mosque, after its conquest in 79 Hijri. Thus the closest date is 84 Hijri (703 CE), and what El-Habhab did was in fact enlarge the mosque and improve its architecture.
For almost two centuries (1812 - 2011), the majority of the Grand Imams of the Zitouna mosque were part of the Cherif and Mohsen families, notably including AbdelKebir Cherif, Ahmed Cherif, Mohamed Cherif, Hamda Cherif, Hassan Cherif, Mahmoud Mohsen, Mohamed Mohsen, and Mostafa Mohsen. The Cherif and Mohsen families are part of the aristocracy "Tunisoise" of Tunis Carthage; are descendants of the Islamic prophet, Mohamed; and are a dynasty of religious scholars, sheikhs, imams, and landowners. These families were founded by an ancestor who arrived in Tunis by the XIV-e century. The descendants of Sheikh Mohsen Cherif changed the line from Cherif to Mohsen, creating the Mohsen branch out of the Cherif line.
Scholarship and the University.
For centuries, Qirwan was the early centre of learning and intellectual pursuits in Tunisia and North Africa in General. Starting from the 13th century, Tunis became the capital of Ifriqiya under Almohad and Hafsid rule.
This shift in power helped al-Zaytuna to flourish and become one of the major centres of Islamic learning, and Ibn Khaldun, the first social historian in history was one of its products.
The flourishing university attracted students and men of learning from all parts of the known world at the time. Along with theology; mainly the Qur'an, the university taught jurisprudence, history, grammar, science and medicine. When it comes to books and libraries, Ez-Zituna libraries were the richest among North African counterparts. It had several collections totalling in the tens of thousands of books. One of its libraries, el-Abdaliyah included a large collection of rare and unique manuscripts. The manuscripts covered almost all subjects and sciences, including grammar, logic, documentations, etiquette of research, cosmology, arithmetic, geometry, minerals, vocational training, etc.
Architecture.
Ez-Zituna mosque followed the design and architecture of previous mosques, mainly the Mosque of Uqba, and was an inspiration for later mosques such as the Great Mosque of Cordoba. The courtyard is accessible via nine lateral doorways and forms a rectangle surrounded by galleries supported by columns made variously of marble, granite or porphyry and which were taken from ancient monuments (primarily from Carthage), as were those in the prayer hall. The square minaret rises from the northwest corner of the courtyard. Built in 1894, the minaret is high and imitates the decoration of the Almohad minaret of the Kasbah Mosque with its limestone strap-work on a background of ochre sandstone. 
Presidents Bourguiba and Ben Ali carried out major restoration work and rehabilitation, especially during the 1960s and 1990s. The dome was added by the Zirids around 991. A beautiful structure about 12 metres in height and 4 metres in width, the dome is considered to be one of the most beautiful domes in Tunis. It fuses Fatimid structural and decorative elements from North Africa as well as Cairo, and has designs similar to the Al Anwar Mosque in cairo. During this time, a courtyard containing arches of the Magrebi horseshoe style was added along with Byzantine style columns thought to be imported from older structures