This paper reported on the design of skyscrapers in the “Conservation Integrated Redevelopment Project” for preserving historic buildings and constructing skyscrapers. In case of the Mitsui Main Building block redevelopment project, we focused on the detailed design of the tower part of the skyscraper “Nihonbashi Mitsui Tower” with a tower-on-the-base type format. Regarding the detailed design, we reported the design process and planning intention from the initial plan to the realization plan. In particular, the design architects’ studies on horizontal fins, capitals, louvers, sunshades, details of hotel floors, shoulders, etc., factors for judgment, issues and policies were summarized.
