Mount Kōya (高野山 Kōya-san) is the name of mountains in Wakayama Prefecture to the south of Osaka. Also, Kōya-san is a modifying word for Kongōbu-ji. There is no one mountain officially called Kōya-san in Japan.
First settled in 819 by the monk Kūkai, Mt. Kōya is primarily known as the world headquarters of the Kōyasan Shingon sect of Japanese Buddhism. Located in an 800m high valley amid the eight peaks of the mountain (which was the reason this location was selected, in that the terrain is supposed to resemble a lotus plant), the original monastery has grown into the town of Kōya, featuring a university dedicated to religious studies and 120 temples, many of which offer lodging to pilgrims.
In 2004, UNESCO designated Mt. Kōya, along with two other locations on the Kii Peninsula, Yoshino and Omine; and Kumano Sanzan, as World Heritage Sites "Sacred Sites and Pilgrimage Routes in the Kii Mountain Range".