the Caliphate of Córdoba and instead prioritized a greater balance between proportions and ornamentation. The two centers of artistic production in the Islamic west before the rise of the Almoravids were Kairouan and Córdoba, both former capitals in the region which served as sources of inspiration. The Almoravids were responsible for establishing a new imperial capital at Marrakesh, which became a major center of architectural patronage thereafter. The Almoravids adopted the architectural developments of al-Andalus, such as the complex interlacing arches of the Great Mosque in Córdoba and of the Aljaferia palace in Zaragoza, while also introducing new ornamental techniques from the east such as muqarnas ("stalactite" or "honeycomb" carvings). After taking control of Al-Andalus in the Battle of Sagrajas, the Almoravids sent Muslim, Christian and Jewish artisans from Iberia to North Africa to work on monuments. The Great Mosque in Algiers (c. 1097), the Great Mosque of Tlemcen (1136) and al-Qarawiyyin (expanded in 1135) in Fez are important examples of Almoravid architecture. The Almoravid Qubba is one of the few Almoravid monuments in Marrakesh surviving, and is notable for its highly ornate interior dome with carved stucco decoration, complex arch shapes, and minor muqarnas cupolas in the corners of the structure. The central nave of the expanded Qarawiyyin Mosque notably features the earliest full-fledged example of muqarnas vaulting in the western Islamic world. The complexity of these muqarnas vaults at such an early date – only several decades after the first simple muqarnas vaults appeared in distant Iraq – has been noted by architectural historians as surprising. Another high point of Almoravid architecture is the intricate ribbed dome in front of the mihrab of the Great Mosque of Tlemcen, which likely traces its origins to the 10th-century ribbed domes of the Great Mosque of Córdoba. The structure of the dome is strictly ornamental, consisting of multiple ribs or intersecting arches forming a twelve-pointed star pattern. It is also partly see-through, allowing some outside light to filter through a screen of pierced and carved arabesque decoration that fills the spaces between the ribs. Aside from more ornamental religious structures, the Almoravids also built many fortifications, although most of these in turn were demolished or modified by the Almohads and later dynasties. The new capital, Marrakesh, initially had no city walls but a fortress known as the Ksar el-Hajjar ("Fortress of Stone") was built by the city's founder, Abu Bakr ibn