The Rakuyo Kannon Pilgrimage covers 33 temples dedicated to Kannon in Kyoto city. Kannon (sometimes Kanzeon or Kwannon) is the Japanese name for the bodhisattva Avalokitasvara, or Bodhisattva of Compassion, one of whose 33 manifestations (the only female one) corresponds to the Chinese bodhisattva Kuan-yin, known in the West as the "Goddess of Mercy."
Kannon's ability to take 33 different forms is the reason why there are 33 temples on this pilgrimage in Kyoto.
For those who intend to do the pilgrimage, here is a list of temples.
The basic procedure at each temple is to have your nokyocho inscribed and stamped at the nokyo (pilgrim's office), which will cost 300 yen. Then find the hall with the Kannon image, toss some money into the donation box, ring the bell (actually a kind of gong that you strike with a vertical rope) three times and say a prayer. You may also light three incense sticks or three candles, the number representing the Buddha, the Dharma and the Sangha.