There was a devotee named Narayana reached venkatachala shrine, he was attracted to the beauty of the hill.

He was immensely delighted to watch the waterfalls and bathe in the gliding brooks.

He bathed in the holy water of swami pushkarani, and intensely mediated upon the Vyuha lakshmi resting on chest of the lord.

When lord appeared before him, Narayana implored him thus:”oh Lord! Venkatapathi! This is my desire! Let this hill be known with my names as Narayanadri.

Also may you descend on this hill to protect the devotes with your dharshan