is a Tendai monastery located on Mount Hiei in Otsu, overlooking Kyoto. It was founded during the early Heian period. The temple complex was established by Saicho (767–822), also known as Dengyo Daishi, who introduced the Tendai sect of Mahayana Buddhism to Japan from China. Enryaku-ji is the headquarters of the Tendai sect and one of the most significant monasteries in Japanese history. As such, it is part of the UNESCO World Heritage Site "Historic Monuments of Ancient Kyoto (Kyoto, Uji and Otsu Cities)". The founders of Jodo-shu, Soto Zen, and Nichiren Buddhism all spent time at the monastery. Enryaku-ji is also the home of the "marathon monks."