There are 88 small temples on one of the mountains behind Ninna-ji Temple. These temples were built as an homage to the very famous 88 Temples on the island of Shikoku. While visiting all of the full-sized temples of Shikoku is the preferred option, the mini-pilgrimage was created for those who cannot make the journey.
The mini-pilgrimage route is built on a mountain, and so it is always open. However, there are only certain days when it is possible to collect evidence of your visit to each temple by completing a stamp book. These days are referred to as the 88-Temple Walk days, and they held once each month during late spring into summer and fall. The Walk is sometimes canceled due to inclement weather, however, so there are often less chances to participate each year than planned. The walk is scheduled on Sundays.
The remaining 88-Temple Walk Days are as follows:
September 9th ・ October 14th ・ November 11th
To collect stamps, go to Kondo (the Main Hall of Ninna-ji) between 9-12 on the day of the walk, and purchase a stamp book for 300 yen. You will then be pointed in the direction of the hiking path. Collect stamps from each temple along the 3 km route to complete the walk.
I recommend the walk for visitors who have a lot of time to spend in Kyoto and enjoy hiking and the outdoors. No reservations are required, just come to Kondo the day of the walk and start hiking!
Ninna-ji Official English Blog 