VOL.200 FEBRUARY 2025
HISTORIC JAPANESE PUBLIC ARCHITECTURE OF THE MODERN ERA One of the World’s Largest Wooden Structures: The ‘Grand Roof (Ring)’ at Expo 2025 Osaka, Kansai, Japan

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Perspective drawing of the Grand Roof (Ring)
©Expo 2025

Expo 2025 Osaka, Kansai, Japan¹ set to begin in April 2025, will feature a symbolic structure called the Grand Roof (Ring) (hereinafter, the “Grand Ring”). Recognized as one of the world’s largest wooden structures, we spoke with the architect responsible for its design.

Expo 2025 Osaka, Kansai, Japan will be held from April 13 to October 13, 2025, lasting approximately six months, at Yumeshima (Konohana Ward, Osaka City, Osaka Prefecture). The Grand Ring, a wooden structure, symbolizes this Expo’s theme, ‘Designing Future Society for Our Lives,’ and has attracted considerable attention. This massive, ring-shaped structure, with a circumference of about two kilometers, covers an area of approximately 60,000 square meters, stands between 12 and 22 meters in height, has an inner diameter of about 615 meters, and is 30 meters wide. The fact that such a large-scale structure is made of wood has also generated significant interest. Sou Fujimoto, the architect responsible for the design of the Grand Ring and the Expo Site Design Producer, shares his insights.

“When creating the overall concept for the Expo site, we proposed and developed the theme of ‘Unity in diversity’ while designing the venue. The messages and significance of the Expo reflect the value of countries from all over the world spending six months together, a place where diverse worlds connect, a future created through real encounters with the world for children and young people, and the global promotion of the Osaka, Kansai, and Japan brands. We aimed to create a venue concept that will remain in the memories of many people. The Grand Ring is a symbolic gateway welcoming visitors, designed with the hope that they will experience its significance and message.”

We asked Fujimoto about the role of the Grand Ring at the Expo site: “The Ring Ground Walk and Ring Sky Walk form a circular route that allows people to move freely. It features a main flow line to avoid congestion, and serves as shelter from rain, wind and sun, while also incorporating multiple navigation systems, including signage. This circular route is designed to spark curiosity about what lies beyond. From the elevated Sky Walk, visitors can enjoy views of the calm waters of the Seto Inland Sea at sunset and panoramic distant views of Osaka and Kobe. Gazing skyward, you will see a clear, unified sky. I hope visitors will feel that this sky is shared by everyone in the world, full of diversity. I aim to integrate these many features into the site’s landscape, ensuring they remain in everyone’s memory and contribute to creating a strong identity that will define this Expo.”

Japan has many wooden buildings with a history spanning over 1,000 years, showcasing traditional construction methods that are a source of national pride. While applying these traditional techniques, the cutting-edge wooden structure also skillfully arranges metal components to meet modern earthquake standards as well as safety standards appropriate for its enormous scale.

“We adopted a construction method based on the traditional kakezukuri² technique used in Kyoto’s Kiyomizu-dera Temple, while incorporating cutting-edge technologies. We hope that showcasing the future of wooden architecture will demonstrate that Japan is leading the world in this field. After seeing the Grand Ring, we hope visitors will be inspired to visit Nara and Kyoto, where they can feel the continuation of this tradition in the modern era,” says Fujimoto.

How about experiencing a walk around the massive Grand Ring during the Expo, from April 13 to October 13, 2025, and enjoying the blend of cultures from various countries, along with the charm and significance of the event?

• 1. Following Japan World Exposition Osaka 1970, the first held in Asia, and the 2005 World Exposition, Aichi, Japan, the Expo 2025 Osaka, Kansai, Japan will be the first international exposition held in Japan in 20 years.
• 2. A traditional Japanese construction method, primarily used in temple and shrine architecture, Kakezukuri refers to the technique of building temples and other structures on steep slopes or cliffs, or the buildings constructed using this method. Kakezukuri involves securely connecting horizontal reinforcing beams between the columns, creating a strong foundation beneath the floor. A base is placed on top of the columns, and the structure of the building is then erected above it. The crisscrossing wooden framework supports itself, dispersing impact and ensuring high durability.

By TANAKA Nozomi
Photo: Expo 2025

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