The term "riad" or "riyad" (from Arabic: رياض‎) refers to a common type of interior garden, in particular one that is symmetrically divided into four parts along its central axes and typically has a fountain at its middle.[64] Interior gardens were a popular feature of palace architecture in the Islamic world because water and greenery were associated with images of paradise in Islam.[6] The earliest known example of a true riad garden (with a symmetrical four-part division) in Morocco was found in the Almoravid palace built by Ali ibn Yusuf in Marrakesh in the early 12th century.[65] This model of interior design became particularly successful and common in Marrakesh thanks to the combination of warm climate and available space, making it well-suited to the architecture of the wealthy mansions and palaces built throughout the city's history.[6] The central gardens of traditional riads were often planted with fruit trees such as orange trees or lemon trees.[1][2]