Mount Kōya is a mountain in Wakayama prefecture to the south of Osaka, Japan, primarily known as the headquarters of the Shingon sect of Japanese Buddhism. First settled in 816 by the monk Kūkai as a retreat far away from the courtly intrigues of Kyoto, Mt. Koya is located in a 800m-high valley amid the 8 peaks of the mountain. The original monastery has grown into the town of Koya, featuring a university dedicated to religious studies and over 100 temples, many of which offer lodging to pilgrims.
In 2004, UNESCO designated Mt. Koya as part of a wider World Heritage Site. If you stay in Osaka, you can consider visit mount Kōya on a day trip (leave early in the morning and allow the time to reach Osaka Namba station and buy your ticket). You can also spend the night in one of the numerous temples (see section).
Many of the pilgrims visiting Mount Koya are on their way to start the 88 Temple Pilgrimage on the island of Shikoku.