Sazae-do, shell shape building, architects ideal building, only one in the world.
Double helix temple. You can go up and down without see somebody.
The Sazae-do is a 16.45m hexagonal wooden tower, built in 1796 at the wishes of Ikudo, a Buddhist-priest. In shape it resembles the spiral-shaped shell of a marine snail called a sazae in Japanese hence its name. Inside the structure there are 33 images of the Buddhist Goddess of Mercy, Kannon. A unique feature of the building are the spiral staircases built in such a way that you never have to retrace your steps as you go up and down them. It was designated a National Cultural Treasure in June 1996.
The staircase has a double helical form, allowing the visitor to travel up and back down without passing the same point twice. Although formally unique, Sazae-do is structurally typical of traditional Japanese timber construction. Wooden posts and beams are connected using variations of common joining techniques.