In 1967, Yukari Bunka Kindergarten by Kenzo Tange was established. The architect choose  the spatial dimension to be comfortable to the children’s scale. The plan of the kindergarten has a radial arrangement. Each roof unit has in a strict sense a shape of a cone rather than a circular cylinder. In the original design the roof was to consist of prefabricated prestressed members. It was found, however, that some parts of the streets connecting the factory and the building site were too narrow to accommodate transportation of the prefabricated roof units. Therefore, we decided to “prefabricate” them in the site.