The Sri Ranganthaswamy temple in Srirangapatna, in the Indian state of Karnataka, is a temple dedicated to the Hindu God Ranganatha, a manifestation of Vishnu and is one of the Pancharanga Kshetrams. The town of Srirangapatna, which derives its name from the temple, is located on an island in the river Kaveri. The temple is one of a set of three major temples that are built on three different islands on the Kaveri and are dedicated to lord Ranganatha.

Ranganathaswamy Temple : The temples is one of the most important Vaishnavite shrines in South India. It is built by the Gangas in 9th century, later improved by the Hoysala and Vijayanagar kings. The temple is a tribute to Lord Ranganatha(Vishnu ) has been dedicated at three pilgrimages

Adi Ranga at Srirangapattana Madhya Ranga at Shivanasamudra Antya Ranga at Srirangam

The Paschima Vaahini section of the Kaveri at Srirangapattana is considered especially sacred; the pious come from far and wide to immerse the ashes of the departed and perform obsequies to their ancestors in these waters.

Source: http://en.wikipedia.org/