The main hall stands 15 meters tall and has a roof made of hinoki (Japanese cypress) bark covering an area of 400 tsubo (about 1,320 m2). The architectural style of the building is unique because the roof covers the front shrine as well as the main hall, and this design has become known as Gion-zukuri (Gion construction style). It has been said that Yasaka Shrine got its start in the early part of the Heian Period when Fujiwara-no-mototsune constructed the Kankei subtemple, Kanjin hall, and the main hall on the grounds. The present structure was rebuilt in 1654 by the 4th Tokugawa Shogun, Tokugawa Ietsuna. Legend says that under the main hall (designated a registered important national cultural property) there is a bottomless pond that a blue dragon uses as its lair, drawing energy from the ancient water and acting as guardian for the ancient city of Kyoto. In addition, because the crest of Yasaka Shrine resembles the cross-section of a cucumber, there is a custom in Kyoto that prohibits eating cucumbers during the Gion Matsuri festival period.