Izumo-taisha, also known as Izumo Grand Shrine or Izumo Ōyashiro, is one of the oldest and most important Shinto shrines in Japan. Its exact establishment date is unknown. Located in Izumo, Shimane Prefecture, the shrine is dedicated to the gods , who is known as the Shinto deity of marriage, and Kotoamatsukami, a group of heavenly deities. The shrine is famous for two major festivals held there. Many people believe that it is the oldest Shinto shrine in Japan, even older than the Ise Grand Shrine.
Izumo-taisha's main hall, called taisha-zukuri, is a style of architecture that takes its name from the shrine. The main hall and the attached buildings were designated National Treasures of Japan in 1952. According to tradition, the hall was once much taller than it is now. The discovery of the remains of enormous pillars in 2000 supports this tradition.
To maintain the power of the kami and preserve architectural techniques, Izumo-taisha has been rebuilt every 60 to 70 years. This process of regular rebuilding is called "Sengū" (遷宮) and is also practiced at other important Shinto shrines, such as the Ise Grand Shrine, which is rebuilt every 20 years.