One should know the significance of the Holy Hills, It is mentioned in Sri Venkateswara Suprabhatam, the range of 7 hills are known as Seshalam, Garudachalam, Venkatadri, Narayanadri, Vrishabhadri, Anjanadri,Neeladri and represents the great serpent bed , Adisesha.
According to Puranas, the Venkatachalam was a part of the Meru mountain in Vaikuntam. It was brought to the earth as a result of a contest between Vayu and Adisesha. Vayu was asked to blow off the Meru mountain which was being protected by Adisesha. When Sesha raised one of his hoods for a moment, Vayu blew off one of the peaks and it landed on earth on the banks of Swarnamukhi. Vem means sin . and Lord Venkateswara manifested Himself here, knowing that people in Kaliyugam will not have the necessary faith and capacity to engage themselves in severe penance and out of His immeasurable mercy, agreed to remain here to redeem them by His Darsan itself . It was Brahma who first started worshiping the Lord when he took “Archavatara” in Kaliyuga.
The range of hills were known by various names in various yugas as follows
VRISHACHALAM” in Kritta Yugam-as Vrishabasura did penance
ANJANADRI IN TRETA YUGAM- as Anjana did penance for begetting Hanuman
SESHACHALAM IN DWAPARA YUGAM- as Adisesha did penance
VENKATACHALAM IN KALIYUGAM –as all sins get destroyed.
According to puranas, Srisailam which is one of the holy shrines dedicated to Lord Siva is Adisesha’s tail, Ahobilam, the famous Narasimha kshetram is (another Siva kshetram) is Adisesha’s mouth. It is believed that Lord Siva along with his consort, stays at Srikalahasti and offers prayers to Lord Venkateswara. As Nammazhwar (is one of the twelve azhwar saints of Tamil nadu, South India, who are known for their affiliation to Vaishnava tradition of Hinduism) says, when we are old and sick, we may not be able to think of Lord Venkateswara. Azhwar says that when we are hale and healthy, we have to fall at His Holy feet and take refuge in Him. Hence, when we are physically fit, we must trek the Holy hills and all our sins will get vanished . In another pasuram, the Azhwar says that at least once in one’s life time, one should go to Tirumala and receive the blessings of the Lord.