This article illustrates the production process, the structural calculations and the assembly phases of the wooden walls of the Japan Pavilion at Expo 2015 in Milan, designed by Atsushi Kitagawara Architects (AKA). The pavilion, one of the most popular construction of this international event, was built almost exclusively with precast interlocking. The production process and the assembly phases were optimized to construct the wooden walls (with a height of 4-12 m) in a short time frame and with a high level of quality. Out-of-plane rocking and other aspects of structural safety were considered, to ensure sufficient stability of the walls.