It is also known as Narasimha Zarna Cave temple, and Jharani Narasimha Temple. This famous cave temple in Bidar district of Karnataka enshrines the powerful deity Lord Narasimha on the wall at the end of a cave, and it is an architectural wonder. It is believed that the shrine at Narasimha Jheera Cave Temple is a swayambu (self-manifested) roopam. A perennial stream of water is said to be flowing continuously for hundreds of years in this place. It is a thrilling experience to walk through waist deep water for 300 meters through a cave-like tunnel, to seek a view of Lord Narasimha. It is one of the main attractions of Bidar.

The legend goes that, Lord Narasimha after killing Hiranyakashpu, proceeded to kill a demon named Jalasura. Jalasura was a staunch devotee of Lord Shiva. After he was killed by Lord Narasimha, Jalasura turned into water and started flowing from Lord’s feet. And to this day water keeps flowing from lord’s feet and fills the cave.

Source:

http://murpriya.blogspot.in/2011/02/narasimha-cave-temple-in-bidar.html