Standing as the architectural centrepiece of Expo 2025 Osaka, Kansai, Japan, The Grand Ring is not only a feat of engineering but also a bold expression of sustainable design and cultural symbolism. Designed by Sou Fujimoto Architects and supported by a team of Japanese architectural and engineering firms, this circular timber structure has officially been recognised by Guinness World Records as the largest wooden architectural structure in the world, with a footprint of 61,035.55 m².

A Landmark of Unity and Circular Thinking
Encircling the Expo site on Osaka’s Yumeshima island, The Grand Ring is conceived both functionally and symbolically. It acts as the main circulation route for visitors—elevated 12 metres to form the Skywalk—while visually and conceptually embodying the Expo’s theme of “Unity in Diversity.” The structure links pavilions from over 150 countries, forming a closed loop with a 615 m inner diameter and 675 m outer diameter, symbolising global connection.

Traditional Craftsmanship Meets Modern Construction
One of the Grand Ring’s defining features is its use of Nuki joints, a traditional Japanese joinery technique where horizontal beams are slotted into vertical posts without metal fasteners. Typically found in shrines and temples, this method has been reimagined with contemporary engineering to create a structure that is both durable and modular.

Construction was divided among multiple consortia of Japan’s leading contractors, including Obayashi, Shimizu, Takenaka, and others, ensuring precise realisation of the design. The structure is modular and dismantlable, allowing for potential reuse after the Expo—a key principle in circular design and a practical demonstration of how architecture can adapt beyond its original lifespan.

A Showcase of Local Materials and Circularity
Approximately 70% of the timber used in the project was sourced domestically in Japan, primarily cedar and cypress, with the remainder made up of imported Scots pine. This approach reduces transportation emissions, supports local forestry economies, and underscores the architectural potential of biobased, renewable materials.

The 30 m wide wooden ring not only provides structural shelter from rain, wind, and sun but also creates elevated public walkways lined with natural elements such as flowers and vegetation. This integration of greenery enhances biophilic design principles, promoting user comfort and connection to nature—an increasingly important factor in urban and landscape architecture.

Future Possibilities: Temporary Structure, Permanent Legacy?
While The Grand Ring was originally intended as a temporary structure, discussions are underway about its future. Its flexible, modular design makes it a prime candidate for adaptive reuse, either in its current location or elsewhere. Much like Paris’ Eiffel Tower—another World Expo legacy—The Grand Ring could live on as a permanent cultural landmark.

Whether it remains or is repurposed, the project presents a visionary model for architects and designers. It demonstrates how traditional craftsmanship, digital design, biobased materials, and circular construction principles can converge in service of sustainable, large-scale infrastructure.

Source: Expo 2025 Osaka, Sou Fujimoto Architects, Dezeen, New Atlas
Photos: Shinwa Co.