Tenryū-ji (天龍寺?)—more formally known as Tenryū Shiseizen-ji (天龍資聖禅寺?)—is the head temple of the Tenryū branch of Rinzai Zen Buddhism, located in Susukinobaba-chō, Ukyō Ward, Kyoto, Japan. The temple was founded by Ashikaga Takauji in 1339, primarily to venerate Gautama Buddha, and its first chief priest was Musō Soseki. Construction was completed in 1345. As a temple related to both the Ashikaga family and Emperor Go-Daigo, the temple is held in high esteem, and is ranked number one among Kyoto's so-called Five Mountains. In 1994, it was registered as a UNESCO World Heritage Site, as part of the "Historic Monuments of Ancient Kyoto".
In the early Heian period, Empress Tachibana no Kachiko, wife of Emperor Saga, founded a temple called Danrin-ji on the site of present-day Tenryū-ji. The temple fell into disrepair over the next four hundred years. In the mid-thirteenth century, Emperor Go-Saga and his son Emperor Kameyama turned the area into an imperial villa which they called "Kameyama Detached Palace" (亀山殿 Kameyama-dono?).
The name "Kameyama", which literally means "turtle mountain", was selected due to the shape of Mt. Ogura, which lies to the west of Tenryū-ji—it is said to be similar to the shape of a turtle's shell. All Japanese temples constructed after the Nara period have a sangō, a mountain name used as an honorary prefix. Tenryū-ji's sangō, Reigizan (霊亀山?, lit. "mountain of the spirit turtle"), was also selected due to the shape of Mt. Ogura.
On the eastern boundary of the temple grounds lie two gates: Chokushi Gate (勅使門 chokushimon?) and Middle Gate (中門 chūmon?), from which the path to the temple itself leads west. Generally, Zen temple grounds are designed so that they face the south, with major buildings aligned along the north-south axis. Tenryū-ji's layout is an exception to this principle. Sub-temples line both sides of the path, which leads to the lecture hall. There are numerous buildings behind the lecture hall, such as large abbey (大方丈 ōhōjō?), the small abbey (小方丈 kohōjō?), the kitchen, the meditation hall, and Tahō-den (多宝殿?) hall, however, each of these is modern reconstruction.