 The mathematical properties of the decorative tile and stucco patterns of the Alhambra palace in Granada , Spain have been extensively studied . Some authors have claimed on dubious grounds to have found most or all of the 17 wallpaper groups there . Moroccan geometric woodwork from the 14th to 19th centuries makes use of only 5 wallpaper groups , mainly <unk> and <unk> , with <unk> and <unk> occasionally and <unk> rarely ; it is claimed that the " <unk> " method of construction can however generate all 17 groups . 
