A circular wooden structure with a diameter of 700 metres is under construction off the coast of Japan as part of architect Sou Fujimoto's masterplan for Expo 2025 Osaka.

Fujimoto is designing the 60,000-square-metre structure to encircle the site of the upcoming World Expo, which will be located on the artificial island Yumeshima in Osaka Bay.

According to the Expo 2025 Osaka organisers, the structure is intended to serve as a symbol of "one sky" and create a "connection" between the participating countries.

It is being developed by Sou Fujimoto Architects for the international fair in collaboration with fellow Japanese studios Tohata Architects & Engineers and Azusa Sekkei.

Led by Bureau International des Expositions (BIE), Expo 2025 Osaka will be held for six months in 2025, following its opening on 13 April.

Fujimoto has designed the wooden ring as a contemporary interpretation of traditional Japanese timber construction, such as that used to construct the Kiyomizu-dera temple in Kyoto.

It will have a diameter of 700 metres and a circumference of two kilometres, which will form the main circulation route for the masterplan.

While incorporating walkways, the structure will double as a shelter from rain and sun, as well as a rooftop observation deck with seasonal landscaping.

On the ground inside the wooden circle, the Expo 2025 Osaka site will be scattered with pavilions designed by architects for participating nations.

These will be divided across three zones, named Pavilion World, Water World and Green World, alongside a series of plazas to hold events.

The first Expo 2025 Osaka pavilion to be revealed on Dezeen is one designed by Shigeru Ban, recently shared in exclusive images.

The undulating pavilion will be built from paper tubes, bamboo and carbon-fibre-reinforced plastic.

The global World Expo exhibition takes place every five years. The previous edition was Expo 2020 Dubai, which was actually held in 2021 due to the coronavirus pandemic.

It featured pavilions by world-renowned studios including Santiago Calatrava and Foster + Partners.

The visuals are courtesy of Sou Fujimoto Architects.