Kyoto Gion Matsuri is one of the biggest festivals in Japan. It takes place from the 14th to the 24th of July. On the 17th there is a procession of the floats (the floats are called, “Yamaboko”). The floats are enormous wooden structures that are moved entirely by man-power and play gion music ( a traditional Japanese music ).
My personal recommendation is to not go to the procession (unless you are determined), but go during the evenings of the 14th-16th. The floats will be displayed on the street and the street will be free for pedestrian traffic. It’s more fun to go in a yukata (a light summer kimono) when it is cooler outside and there is space to move around.