The Nagano City Wakamiya Multi-purpose Sports Arena Big Hat + Aqua Wing, completed in 1997, stands as a remarkable example of large-scale sports architecture. Designed by the collaborative team of Yamashita Sekkei and Nagano Sekkei, this indoor facility showcases innovative structural design with its distinctive dual-dome configuration. The Big Hat's iconic saddle roof and the complementary Aqua Wing aquatic center represent a cohesive approach to contemporary sports facilities. Located in Wakasato, Nagano, this complex demonstrates the integration of diverse athletic functions within a unified architectural vision, making it an important landmark in Japanese sports facility design from the late twentieth century.