Izumo-taisha (出雲大社, “Izumo Grand Shrine”), officially Izumo Ōyashiro, is one of the most ancient and important Shinto shrines
in Japan. No record gives the date of establishment. Located in Izumo, Shimane Prefecture, it is home to two major festivals.
It is dedicated to the god Ōkuninushi (大国主大神, Ōkuninushi-no-ōkami), famous as the Shinto deity of marriage and to
Kotoamatsukami, distinguishing heavenly kami. The shrine is believed by many to be the oldest Shinto shrine in Japan,
even predating the Ise Grand Shrine.
https://en.wikipedia.org/wiki/Izumo-taisha