These thousand-year-old stone Buddhas lie just outside Usuki. Four clusters comprising 60-plus images (59 are designated National Treasures) lie in a series of niches in a ravine. They're largely made of lava rock from Aso-san. Some are complete statues, whereas others have only the heads remaining. It's truly a spiritual place if it's uncrowded, although some of the magic can be lost in the touristy ambience just outside.
Nearby is a lovely lotus pond (free).