The decorations within the palaces typified the remains of Moorish dominion within Spain and ushered in the last great period of Andalusian art in Granada. With little of the Byzantine influence of contemporary Abassid architecture, artists endlessly reproduced the same forms and trends, creating a new style that developed over the course of the Nasrid Dynasty. The Nasrids used freely all the stylistic elements that had been created and developed during eight centuries of Muslim rule in the Peninsula, including the Calliphal horseshoe arch, the Almohad sebka (a grid of rhombuses), the Almoravid palm, and unique combinations of them, as well as innovations such as stilted arches and muqarnas (stalactite ceiling decorations). The isolation from the rest of Islam plus the commercial and political relationship with the Christian kingdoms also influenced building styles.
El mirador de Lindaraja. Columns and muqarnas appear in several chambers, and the interiors of numerous palaces are decorated with arabesques and calligraphy. The arabesques of the interior are ascribed to, among other sultans, Yusuf I, Mohammed V, and Ismail I.

en.wikipedia.org/wiki/Alhambra