United by the Grand Ring
Expo 2025 in Osaka is welcoming its visitors with a structure that is in a class of its own. Architect Sou Fujimoto has designed the Grand Ring for the World Exposition. It is the world’s largest wooden architectural construction, made with glued laminated timber.
One of the most famous sights in Kyoto is the Kiyomizu-dera, a wooden temple whose existing buildings are almost 400 years old. Looking down from its 13-metre pedestal, there is a spectacular view across the old imperial city and Japan’s main island Honshū. The structure was built according to the construction method known as kakezukuri, which was traditionally used for sloping sites.
In this method, the vertical posts are secured using horizontal beams, forming a traditional Japanese penetration joint (nuki). Altogether, the construction can be best described as huge three-dimensional rung ladders. The method is entirely without any nails or other metal connectors.
Largest glulam construction in the world
This design approach was also used by internationally renowned architect Sou Fujimoto as the basis of his construction for Expo 2025, which opened on 13 April in Osaka on the artificial island Yumeshima in Osaka Bay. Built partly on the island and partly on water, the Grand Ring creates a link between this traditional Japanese timber craftsmanship and today’s high-performance engineered wood technology. The result is a fusion of old and new, combining the best out of these different epochs.
The gigantic ring-shaped construction, which encircles the entire grounds of the Expo, is made up of industrially produced glulam consisting of many layers of wood. With a diameter of over 600 metres and a circumference of two kilometres, the structure has been officially recognized as the world’s largest wooden architectural construction.
The building material of the future
In line with the topic of the World Exposition – “Designing Future Society for Our Lives” – the focus is on sustainability and living within our planet’s limits. Wood was chosen as the building material not just to pay homage to the over 1000-year-old history of Japanese wood construction, but also due to its function as a carbon sink.
It is our firm belief that wooden architecture is the sustainable architecture of the future.
Sou Fujimoto, architect
Sou Fujimoto is in no doubt about the sustainability of this natural building material: “It is our firm belief that wooden architecture is the sustainable architecture of the future. In Japan, home to the world’s oldest wooden building, the Horyu-ji Temple, the combination of ancient traditional and modern technology can show what wooden architecture will look like in the future.”
The future is primitive
It is not just the dimensions of the Grand Ring that are exceptional, however. The architectural language adopted by Fujimoto pursues a new means of communication between people and the space around them. In his theoretical study Primitive Future from 2008, the 53-year-old architect writes about the basics of his architecture, with a cave as the point of departure for his thinking: a primitive space whose function was determined solely by human behaviour.
Fujimoto deconstructs our established ideas of a built environment and breaks them down, in a figurative sense, to reveal their foundations. In his striving for the dissolution of physical space, he softens the opposite nature of interior and exterior, while storeys and dividing walls are reduced to a forgotten expression of spatial inertia. His residential houses are like the branches of a tree, divided into terraced floors that create spatial density while allowing various living situations to be experienced.
If architecture is created like a forest, it will be a place of complexity, rich in diversity, much more than that which exists in the architecture of today’s cities.
Sou Fujimoto, architect
In his considerations, the forest is an ideal place. As Fujimoto explains in Primitive Future: “If architecture is created like a forest, it will be a place of complexity, rich in diversity, much more than that which exists in the architecture of today’s cities.” The future described in his book is naturally not primitive in the sense of uncomfortable, but in the sense of an original state.
Feels like a forest
There is certainly a clear indication that the Grand Ring is referencing a forest landscape. Reaching a height of 12 to 22 metres, the ring structure encircles an area of 60,000 square metres which can be labelled as neither indoor nor outdoor space. The passage created at ground level is a kind of intermediate space. Protected against the elements, visitors to the Expo can come here to stroll from one area to another. The rays of light shining through the high wooden grid construction can be easily likened to the light filtering through the treetops in a forest scene.
The individual timber elements for this 30-metre-wide ring are glulam posts and beams sized 420 x 420 mm and 210 x 420 mm. Visitors can walk along the roof of the Grand Ring, enjoying the lush greenery and views across Osaka, Kobe and the Seto Inland Sea.
“This timber construction roof is part of the main circulation of the Expo master plan, providing spectacular experiences while protecting visitors from rain and strong sunlight,” Sou Fujimoto Architects explain.
People from a wide variety of nations come together at a world exposition, with communication being shaped by a high level of diversity. Describing his hopes for the lasting impression gained by Expo visitors, Fujimoto observed: “My hope is that every visitor will experience ‘unity in diversity’.” The Grand Ring is therefore symbolic of the connection between people.
Text: Gertraud Gerst
Translation: Rosemary Bridger-Lippe
Photos: Expo Osaka 2025, Sou Fujimoto Architects