The muqarnas are small pieces grouped together, adopting surprising three-dimensional forms. They are a symbol of identity of the 14th century Nasrid architecture at Alhambra in Granada. This research's aim is to graphically analyze the plaster muqarnas dome located to the south of the Sala de los Reyes, in the Palacio de los Leones. The methodology followed combines historical images analysis and modern digital graphic techniques. First, a compilation of unpublished drawings and photographs documenting architectural transformations and significant alterations in the roof structures since the 16th century is provided. Although these muqarnas were drawn by Jones and Goury in the 19th century, the current research identifies and draws, digitally for the first time, its nearly two thousand pieces of this dome. Additionally, metric data of the current state has been collected using 3D laser scanning, revealing significant deformations. In this way, the knowledge of these fragile architectural elements is achieved to promote their heritage dissemination and to facilitate the conservation of a monumental site included in the UNESCO World Heritage List.