The most interesting structure at the Garan is the Konpon Daitō, a 50m-tall, bright-vermilion pagoda seated at what is considered to be the centre of the lotus-flower mandala formed by Kōya-san's eight mountains. The main object of worship is Dainichi-nyōrai (Cosmic Buddha), surrounded by four attendant Buddhas and, painted on pillars, 16 bodhisattva, which together compose a three-dimensional mandala of the Shingon Buddhist cosmos.
Originally, it's said, the pillars were painted by Kōbō Daishi himself; the current building (and paintings) date to 1934.