Spring 2025, Yumeshima, the artificial island in Osaka Bay built for World Expo 2025. Drone footage keeps doing the same trick: pull back, and a wooden ring the length of a small city's ring road resolves out of the pavilions underneath it, perfectly circular, people walking along its rooftop promenade like ants on the rim of a wheel. Guinness World Records makes it official on 4 March 2025 — the largest wooden architectural structure ever built, a little over 61,000 square metres of roofed timber, 109 separate wooden frame units bolted and slotted into a circle roughly 615 metres across.
Cut to 5 March 2026. The Expo has been closed for nearly five months. Reporters are invited back onto Yumeshima, and this time the drone shot is a construction crane lowering a beam the size of a telephone pole onto a flatbed, while a contractor in a hard hat explains, politely, that this part of the ring is never coming back.
The structure everyone photographed is called the Grand Ring (大屋根リング), designed by architect Sou Fujimoto around the Expo's theme of "unity in diversity" — one continuous timber loop wrapping the entire site, tall enough to walk under at 12 metres on the inside and 20 on the outer face, wide enough across its deck to stroll along the top. Assembly started on 30 June 2023; the full loop closed into one connected ring on 21 August 2024, nearly eight months before the doors opened. Three of Japan's biggest general contractors — Takenaka, Obayashi and Shimizu — each built a different third of the circle, which is part of why descriptions of its exact height vary slightly depending on which company's section you are standing under.
What makes it more than a very large roof is how it was joined together. The ring leans on 貫接合 (nuki-setsugō) — the horizontal tie-beam joinery that has braced Japanese shrines and temples for over a thousand years, slotted through posts rather than nailed or bolted to them — reinforced with modern seismic engineering to meet current earthquake code. Obayashi's third alone used hinoki cypress for roughly half its pillars and sugi cedar for its beams, the same two woods that have framed this country's religious architecture for centuries, bent here into a shape no shrine carpenter ever had to solve: a perfect, kilometres-long circle.
Here is the detail that never made it into the drone-shot headlines: nobody involved ever planned for this to be permanent. A structure built for a six-month Expo, on reclaimed land earmarked afterward for a casino and resort development, was a temporary building by design from the morning ground was broken. The record-setting part was an accident of ambition, not a decision to build something that would stay.
So when World Expo 2025 closed on 13 October 2025, the dismantling that followed was not a demolition gone wrong — it was the plan, running on schedule. What is genuinely being argued over is what happens to the wood. Roughly 200 metres of the ring's north-eastern arc is being left standing as a walkable monument. A portion of the salvaged timber is earmarked for disaster-recovery public housing in Suzu, a city in Ishikawa Prefecture still rebuilding after the earthquake and the heavy rain that followed it in 2024. Yokohama has floated reusing more of it for its own Green Expo in 2027. And in at least one interview, Fujimoto himself has suggested that a large share of what is left over — by some accounts the majority of it — may simply end up chipped and burned as fuel, because a building engineered to be taken apart in sections does not always come apart into pieces anyone can reuse.
That last detail is what lit the argument. Commentator and entrepreneur Takafumi Horie called tearing the ring down "an embarrassment for Japan"; fellow entrepreneur Yusaku Maezawa publicly pushed back. Underneath the disagreement is the same number, read two different ways: either Japan built something extraordinary and is now feeding chunks of it into a furnace, or Japan built something extraordinary, let several hundred thousand people walk across it for six months, and is now turning the rest into houses for families who lost theirs.
The instinct, watching the footage, is to call this wasteful — a record-breaking building, cut down a year after it went up. But Japan has been doing a version of this on purpose for a very long time. Ise Grand Shrine, one of the country's most sacred sites, has been deliberately torn down and rebuilt from scratch roughly every twenty years for over a thousand years, not because the old shrine failed, but because renewal was always the point. The Grand Ring was never a monument that got cancelled. It was built, from its first beam, on the same clock as a shrine — a structure whose job was to exist spectacularly for a set amount of time and then stop existing, ideally leaving something useful behind. Judged as a monument, tearing it down looks like a loss. Judged by the standard this country actually uses for its grandest wooden buildings, it is simply what happens next.
- Guinness World Records certified the Grand Ring on 4 March 2025 as the largest wooden architectural structure on Earth: a closed loop roughly 615 metres across and 2 kilometres in circumference, roofing a little over 61,000 square metres, assembled from 109 separate timber-frame units.
- It was joined using 貫接合 (nuki-setsugō), the horizontal tie-beam joinery used in Japanese shrine and temple carpentry for over a thousand years, reinforced to meet modern seismic codes rather than built from scratch as a new technique.
- After the Expo closed in October 2025, roughly 200 metres of the ring is being preserved as a walkable monument, and part of the reclaimed timber is earmarked for disaster-recovery public housing in Suzu, Ishikawa Prefecture, still rebuilding after 2024's earthquake and heavy rain.