Located in the periphery of Tiruchirappalli, is the river island town of Srirangam. The town is flanked by the Cauvery river on one side, and its tributary Kollidam on the other. The town is widely known for the ancient and grandiose Sri Ranganatha Swamy Temple. Of the 600 acres across which the town is spread, 156 acres house the temple complex. The temple is also said to be the most important, foremost and first of the 108 main Vishnu temples (divyadesams) as well as the primary of the eight self-manifested shrines (Swayam Vyakta Kshetras) in the country. The complex has seven prakaras (enclosures), which have been formed from huge and thick rampart walls around the sanctum. The annual 21-day festival conducted during the months of December and January attracts up to one million visitors who flock to the compound to experience the festivities and pay their respects to Lord Vishnu.