Thirunallur Temple or Kalyanasundar Temple in Kumbakonam, Thanjavur District, Tamilnadu, India is a pilgrimage that has an unique Shiv Ling (the idol of Lord Shiva).The temple houses a unique Shiv Ling (the main deity) that keeps changing in colors, five times during the day, and some say, it changes for every 2 hoursand 24 minutes. The Shiv Ling takes: copper color (6 am-8.24 am), red(8.25 am- 10.48 am), golden (10.49 am- 13.12 pm), emerald green (13:13 pm-15:36 pm) and, can appear in any color during 15.27 pm-18.00 pm, as per the devotee’s wish. The devotees visiting the temple during these periods can directly witness the color change.
This temple, which has its history dating back to the time of Lord Shiva-Goddess Parvati marriage. According to the temple history, when everyone went for the marriage, there appears an inbalance on the earth and so, the planet tiled. Then, Lord Shiva was said to have asked Sage Agastya to bring a balance, for which, the Sage visited the South of Vindhyas. Disappointed at not witnessing the marriage, Agastya installed an idol beside the already-existing idol in the temple, and started worshipping it. Then Lord Shiva and Goddess Parvati appeared before Agatsya, in the form of groom and bride. The idol currently in the temple is said to be the one installed by Sage Agatsya.
The temple also has idols of Brahma and Vishnu standing on the left and right sides of Shiva-Parvati, performing the marriage rituals, which is rarely seen in the Garbhagruha of any temple.