It is a long-standing human custom to set aside the most beautiful places for a special purpose, and build something. When you look at a landmark building in a magnificent setting such as the Shuri Castle, you see wooden gates and pillars. Think of the comparison between Kyoto's fragile wooden temples and Egypt's enduring pyramids. Then imagine a massive rock base, and a delicate wooden structure set on top of it, the best of both worlds. Okinawan rock is a type that fractures along straight lines.
Fractures can happen naturally, or the process can be helped by the hand of man.
It is likely that the Ryukyuans started with a huge slab of rock already in place, then improved on nature by cutting straight sides and flat terraces in the rock to make foundations for their monuments. Recently, a stone structure was discovered underwater near one of Okinawa's islands, Yonaguni. It has flat terraces on top, and straight sides. Marks made by cutting tools add weight to the idea that this was a natural rock that people altered to create a monument. There are even holes in the upper surface that could hold wooden columns or poles securely in place.