The day I visited Shimogamo Shrine was the day of a summer rite. Shinto priests were making implements for the ceremony at the precinct. One of the priests explained to me that it was a wooden stand to set sacred arrows upon. At the end of the ceremony, selected men scramble for the arrows in the water (Nagoshi Shinji 夏越神事).
There are two ways to go to Shimogamo Shrine; going through Tadasu-no-mori Forest, or directly from the Shimogamo Jinjamae Bus Stop. The latter is the nearest bus stop to go to the shrine, although it is not the formal shrine entrance. If you have enough time, I recommend that you go via the long approach, cutting through the forest. In summertime, kids sketch the scenery and play with water in the stream there.
More info
Find out more about Shimogamo Shrine.