Nipro Hachiko Dome

The Nipro Hachiko Dome is an airy and elegant wooden sports stadium in the city of Ōdate in northern Japan. Built by the acclaimed architect Toyo Ito, it ranks among the largest wooden domes in the world (the largest is the Superior Dome in Marquette, Michigan).

Completed in June 1997, the stadium has a capacity of 15,000 people and is primarily used as a baseball venue. Its semi-removable grandstands allow for a variety of other sports, too, including soccer and tennis, as well as non-sporting events.

The dome was built from the wood of 25,000 Akita cypress trees from the local prefecture, aged for 60 years and cut into planks. The planks were glued together and then covered in a special double Teflon-coated membrane made from a translucent fluoroethylene resin-coated fiberglass. This allows light to pass through the dome, to such an extent that artificial lighting is rarely needed during the day.

The apparent lightness of the structure—which, thanks to its design, seems to almost float above the ground—belies its size. The stadium measures 584 feet by 515 feet along its major and minor axes respectively, with a height of 171 feet. 

The dome was also designed with the local weather in mind, which is highly seasonal. Ōdate has warm to hot (and often humid) summers and sometimes severely cold winters. As such, the dome was designed to allow air to circulate freely, keeping the interior cool during the heat of the summer. The aerodynamic design is also able to resist strong winds and heavy snowfall during the winter. If snow starts to build up on the roof, warm air can be circulated between the two Teflon-coated membranes, keeping the snow under control.