Kongōbuji, or "Temple of the Diamond Peak," is the name that the founder of Mt. Kōya gave to his entire monastic center. Today, however, it refers more specifically to the sprawling complex of buildings that serve as the administrative headquarters for more than 3,600 Shingon temples throughout Japan. The temple that we see today dates back to the late 16th century when the famous feudal lord Toyotomi Hideyoshi established a temple called Seigan-ji in memory of his mother. In the year 1869, this temple merged with Kōzan-ji Temple to become the present-day Kongōbuji.

The temple spreads out over 160,000 square meters and comprises a series of interconnected wings and galleries. These include the living quarters of the Abbot and other priests, formal reception rooms, a scripture library, meditation halls, lecture halls and a large working kitchen for monastery residents. Many rooms feature decorative sliding doors painted by Kanō Tan’yū, one of the most famous Edo-era painters. Among the interior gardens and courtyards, is Japan's largest rock garden.

The "Garden of the Coiled Dragons" (Banryū-tei) is the largest garden of its kind in Japan featuring 140 large rocks emerging from a bed of raked white pebbles. The rocks represent a male and a female dragon rising from a sea of clouds to protect the "Inner Hall" (Okuden). This building, which offers the best view of the garden, is across the way from the balustraded walkway used by visitors. Unfortunately, it is closed to the general public except on special occasions.

The garden, along with the nearby "Shin-Betsuden," was completed in 1984 as part of the 1150th anniversary of Kūkai’s entrance into perpetual meditation. The large rocks representing the protector dragons were brought to Mt. Kōya from the island of Shikoku, where Kūkai was born.