A hidden roof. The roof structure built above an exposed roof. It has its own support system and hidden rafters that are set at a different angle from the rafters of the exposed roof. The earliest example is the hidden roof built in 990 over the aisles *hisashi 廂, surrounding the core *moya 母屋 at Hōryūji *Daikōdō 法隆寺大講堂 in Nara. With a noyane, the base rafters *jidaruki 地垂木, could be given a gentle incline. A base *sasudai 扠首台, was laid across the base rafters and diagonal struts were set upon them to support the purlins that carried the hidden roof. From the 12th century onward, hidden roofs built over entire buildings became common. Examples: Upper Daigoji Yakushidō 醍醐寺薬師堂 (1121), Sanzen'in Hondō 三千院本堂 (1148) both in Kyoto, and Taimadera *Mandaradō 当麻寺曼茶羅堂 (1161) in Nara.