and was split into several small kingdoms called taifas. During this period, art and culture continued to flourish despite the political fragmentation of Al-Andalus. The Aljaferia Palace of Zaragoza is the most significant palace preserved from this period, featuring complex ornamental arcades, multifoil and mixtilinear arches, and stucco decoration. In other cities, a number of important palaces or fortresses were begun or expanded by local dynasties such as the Alcazaba of Málaga and the Alcazaba of Almería. Other examples of architecture from around this period include the Bañuelo of Granada, an Islamic bathhouse. Almoravids and Almohads The late 11th century saw the significant advance of Christian kingdoms into Muslim al-Andalus, particularly with the fall of Toledo to Alfonso VI of Castile in 1085, and the rise of major Berber empires originating in present-day Morocco. The latter included first the Almoravids (11th–12th centuries) and then the Almohads (12th–13th centuries), both of whom created empires that stretched across large parts of western and northern Africa and took over the remaining Muslim territories of al-Andalus in Europe. This period is considered one of the most formative stages of western Islamic (or "Moorish") architecture, establishing many of the forms and motifs that were refined in subsequent centuries. Relatively little survives of Almoravid architecture but much more has survived of Almohad architecture. In Seville, the Almohad rulers built a new Great Mosque (later transformed into the Cathedral of Seville), which consisted of a hypostyle prayer hall, a courtyard (now known as the Patio de los Naranjos or Court of Oranges), and a massive minaret tower now known as the Giralda. The minaret was later expanded after being converted into a bell tower for the current cathedral. Other examples of Almohad architecture are found in various fortifications and smaller monuments in southern Spain today, as well as in traces of the former Almohad palace in the Alcazar of Seville. Almohad architecture promoted new forms and decorative designs such as the multifoil arch and the sebka motif, probably influenced by the Caliphate-period architecture of Cordoba. Nasrid Emirate of Granada As the Almohad authority retreated from al-Andalus in the early 13th century, the Christian kingdoms of the north advanced again and Muslim al-Andalus was eventually reduced to the much smaller Nasrid Emirate centered in Granada, where much of the Muslim population took refuge. The palaces of the Alhambra and the Generalife in Granada, built under the Nasrid dynasty,