Aghlabid architecture
Aghlabid architecture dates to the rule of the Aghlabid dynasty in Ifriqiya during the 9th century and the beginning of the 10th century. The dynasty ruled nominally on behalf of the Abbasid Caliphs, with which they shared many political and cultural connections. Their architecture was heavily influenced by older antique architecture in the region as well as by contemporary Abbasid architecture in the east. The Aghlabid period is also distinguished by a relatively large number of monuments that have survived to the present day, a situation unusual for early Islamic architecture. One of the most important monuments of this period, the Great Mosque of Kairouan, was a model for mosque architecture in the region. It features one of the oldest minarets in the world and contains one of the oldest surviving mihrabs in Islamic architecture.
Historical background
The Muslim conquest of North Africa took place progressively during the 7th century. During this period, the city of Kairouan was founded in 670 and served as the regional capital of the Maghreb. The Great Mosque of Kairouan, the city's congregational mosque, was also initially founded in 670. The Abbasid revolution in 750 put the Abbasid Caliphs in overall control of the Islamic empire, overthrowing the previous Umayyad Caliphs. In Ifriqiya, several rebellions and attacks on Kairouan, mainly from the Kharijites, had to be suppressed.In 800 the Abbasid caliph Harun al-Rashid appointed Ibrahim ibn al-Aghlab as governor of the entire Maghreb. He founded the Aghlabid dynasty, who ruled Ifriqiya nominally on behalf of the Abbasid Caliphs in Baghdad but were de facto autonomous. In practice, their political power was mainly concentrated in the region of Ifriqiya. Under their rule, Kairouan grew into the major cultural and spiritual center of Sunni Muslims in the Maghreb. Although this city was in principle the political and economic capital, the Aghlabid rulers themselves usually resided in other nearby sites purpose-built for housing the government. Sources claim that after coming to power in 800, Ibrahim ibn al-Aghlab's first action was to found a new royal residence, al-Abbasiyya, just southeast of Kairouan. It was built between 801 and 810, and included its own congregational mosque and palaces.
Under the rule of Ziyadat Allah I, one of the most competent rulers of the dynasty, the Aghlabids embarked on a campaign of conquests in the central Mediterranean, including the conquest of Sicily, the conquest of Malta, and expeditions to the Italian mainland. In 876 Ibrahim II ibn Ahmad moved the royal residence from al-Abbasiya to a new palace-city he founded, named Raqqada, again near Kairouan. The city contained a mosque, baths, market, and several palaces. He resided in a palace called Qaṣr al-Fatḥ, which remained the residence of his successors.
Kairouan, as the center of Aghlabid power, received significant attention and patronage. The Aghlabid rulers concerned themselves with furnishing cities with water – seen as a pious duty – and with building or rebuilding mosques as physical expressions of the dynasty's presence and legitimacy. The founding of new royal cities or residences, such as al-Abbasiya and Raqqada, also had symbolic value as part of the dynasty's portrayal of its own power, while probably also serving to distance it from social and political tensions within Kairouan. Former Christians, converted to Islam, also played a central role in the field of architecture in Ifriqiya during this era. Some of them were freed slaves, known as mawali, who continued to serve their former masters, often serving as supervisors in the construction projects sponsored by their masters.
Aghlabid rule began to weaken by the end of the 9th century and in 909 they were finally overthrown by a Kutama army led by Abu Abdallah al-Shi'i, establishing the new Fatimid Caliphate with Ifriqiya as its heartland.
General characteristics
The century of Aghlabid rule saw a degree of political stability and continuity that allowed architectural patronage to flourish. The relatively large number of surviving monuments from this period in one region is unusual for this era of Islamic architecture, allowing for a more detailed study of their architectural development.Aghlabid architecture remained heavily influenced by the traditions of Antiquity, evidenced by the continuing extensive use of stone and some associated decorative techniques. The ruins of Roman Africa were also frequently reused as a source of building materials, particularly for marble and cut stone. The Aghlabids' connection to the Abbasids in Baghdad also meant that they imported or adopted the latest techniques from the metropolitan Abbasid style in Iraq, as seen in the luster-painted tiles of the mihrab in the Great Mosque of Kairouan, the carved stucco decoration in Raqqada, and the stone-carving of the Mosque of Ibn Khayrun.
The use of the horseshoe arch in Ifriqya is evident in this period, though the form is not as pronounced as it was in other periods and regions of Moorish architecture. Some of the smaller arches, especially for mihrabs and in decorative compositions, have one continuous curve, but most of the time the arches were slightly pointed or deformed near their upper summits.
File:A Driving Tour of Kairouan, Tunisia.jpg|thumb|Kufic inscriptions and vegetal ornamentation carved on the stone façade of the Mosque of Ibn Khayrun in Kairouan
During the Aghlabid period, the beginnings of geometrically arranged arabesques can begin to be discerned, but this decorative technique was to be significantly enriched in later periods. The geometric motifs typical of later Islamic art did not yet occupy a prominent role. Arabic inscriptions carved in Kufic script were sparsely but widely used in decoration as well. Various vegetal compositions of leaves and stems are attested in this period, with the designs differing depending on whether they were filling elongated friezes or larger panels. One decorative motif specific to the Aghlabid period is the use of floral rosettes set inside squares, circles, or lozenges. These motifs were carved in stone and found in the mosques of Kairouan and Sousse. The square tiles on the mihrab of the Great Mosque of Kairouan are also arranged in a pattern that recalls this motif.
While many columns and capitals were reused from ancient buildings, some of the capitals of columns and colonettes found in Aghlabid mosques appear to be contemporary creations of the Aghlabid period. They have a simple and broadly carved decoration of leaves on each side of the capital, ultimately inspired by ancient Corinthian models. They also resemble examples from Egypt, which Georges Marçais suggested may indicate a general style used in Islamic North Africa during this era.
Fortifications
Forts and ribats
The threat of Byzantine attacks by sea encouraged the construction of forts and fortifications along the coast of Ifriqiya. Ribats were one type of structure which proliferated under Aghlabid rule. They served as residential fortresses and religious retreats, simultaneously a defensive structure and a kind of Muslim monastery where pious warriors gathered for jihad. They were typically square or rectangular fortified enclosures with interior courtyards surrounded by chambers and communal rooms. They were built at regular intervals along the coast. Medieval geographers claimed that the ribats were built at precise distances from each other to allow signals to be passed from one to the other using mirrors and fires, thus allowing messages to travel rapidly along the North African coastline. The remains of many ribats and other small fortifications are still found along the Tunisian coastal areas. Many of them were built over former Roman or Byzantine fortifications or were former Byzantine forts restored by the Muslim garrisons. The influence of Byzantine architecture continued to be evident in the fortifications built by the Aghlabids.Of the many ribats built during this era, the Ribat of Sousse and the Ribat of Monastir are the most impressive surviving examples. They are dated to the late 8th century, making them the oldest surviving Islamic-era monuments in Tunisia – although they were both subjected to later modifications. The Ribat of Monastir was founded in 796 by the Abbasid governor Harthama ibn A'yan, but it has gone through multiple modifications, restorations, and expansions, making the chronology of its construction difficult to outline. It gained prestige over time as a teaching place, as a religious retreat, and as a burial place.
The Ribat of Sousse, founded during the tenure of the Abbasid governor Yazid ibn Hatim al-Muhallabi, is built of stone and consists of a square walled enclosure measuring around 38 meters long and 11 meters high. Round towers reinforce its corners and the middle of its four sides, except for the southeastern corner, where a square tower serves as the base for a tall cylindrical tower on top of it. In the middle of the south side a projecting rectangular salient serves as the entrance gate. The gate is framed by reused ancient columns. Inside the gate are narrow openings for a former portcullis and for defenders to drop projectiles or boiling oil on attackers. Guardrooms were connected to the vestibule. The gate leads to the courtyard, which is flanked by arcades on each side, behind which are lines of small rooms and an upper floor. On the south side of this upper floor is a vaulted room with a mihrab which is the oldest preserved mosque or prayer hall in North Africa. Another small room in the fortress, located above the gate, contains another mihrab and is covered by a dome supported on squinches. This is the oldest example of a dome with squinches in Islamic North Africa. The cylindrical tower above the southeast corner was most likely intended as a lighthouse. It can be ascended via a spiral staircase inside. It has a marble plaque over its entrance inscribed with the name of Ziyadat Allah I and the date 821, which is the oldest Islamic-era monumental inscription to survive in Tunisia. This date has been interpreted by some scholars as the foundation date of the whole ribat rather than the construction date of the tower only, or as the date of a reconstruction.