Aoi Matsuri is one of the greatest festivals in Kyoto. It's held on May 15 every year. The main attraction is a procession of about 500 people in Japanese ancient court costumes. The procession starts from Kyoto Imperial Palace and goes to Shimogamo Shrine and to Kamigamo Shrine.
Kyoto Aoi Matsuri
Japanese Fall Festivals
Kyoto Imperial Palace Photo (c) Shizuko Mishima, licensed to About.com