According to Puranas Seven heads of Adishesa are the Seven Hills of Tirumala. The Seven peaks are called as Seshadri, Neeladri, Garudadri, Anjanadri, Vrishabhadri, Narayanadri, Venkatadri.
Most important peak among the Saptagiris is Seshadri. Seshadri is named after Adishesa, divine Serpent on whom Lord Vishnu rests. There is a story behind this hill. During Dwapara Yuga, Vayu (wind god) reached Vaikuntam to visit Lord Vishnu. Adisesha did not allow him inside as Lord Vishnu was taking rest with his consort Lakshmi Devi. Vayu was not ready to go back without visiting Lord Vishnu, and they started to argue with each other. Lord Vishnu himself came to them, but they still continued the argument, that one is better than the other. Finally Lord Vishnu said Adishesa should hold the Anadha Shikara, one of the peaks of Meru Mountain and Vayu should try to blow off Adishesa from Meru Mountain. Who ever wins they will be declared stronger than the other. So, Adishesa held Meru Mountain tightly by coiling around it and Vayu tried to move it. Vayu used all his power to blow away the mountain but he could not move it. After sometime out of curiosity, Adisesha wanted to see what Vayu is doing and it lifted its head. In a fraction of second Vayu moved Anadha Sikaram along with Adishesa and dropped it at banks of river Swarnamukhi. According to Bhavisya Puranam this hill is called as Seshadri or Seshachalam.
First devotee who gave her hair to god is NeelaDevi. Lord Srinivasa named this hill by her name as Neeladri. When Lord Srinivasa was hit by a Shepard on his head, a small portion of his scalp becomes bald. There is no hair growth over that place and this was noticed by Gandharva princess, Neeladevi. She felt such a handsome face should not have any defect. Immediately she cuts a portion of her hair and implants it on his scalp with her powers. As hair is considered as the beautiful aspect of women, Lord Srinivasa notices her sacrifice and he said all the hair given to him by devotees in Tirupathi belongs to Neeladevi. Giving our hair to god is the symbol of leaving our ego. The word “Talanelalu” is also came from her name. Many devotees give their hair to Lord Balaji. The daily quantity of hair collected is over one ton. This hair is sold by the temple organization by auction.
Kesari, the king of Vanaras (monkeys), married Anjanadri. They were childless for many years. So Anjanadri went to a hill near Akasa Ganga and did penance for several years. Later Vayu (wind god) gave a fruit to Anjanadri. As a result of eating that fruit given by Vayu she gave birth to Lord Hanuman. As Anjanadri did penance on this hill it is called as Anjanadri.
In Kruthayuga, near Thumbura Theertha in Tirumala there lived a demon named Vrushabhasura. He is a devotee of Lord Siva. He used to cut his head daily and offer it as prasadam to Lord Siva. Every time as soon as he cut his head he used to get a new head. Lord Siva was pleased by his prayers and came before him. Vrushabhasura asked Lord Siva to fight with him. Lord Siva accepted it and the war went on for many days. Finally Vrushabhasura was defeated. Before dying as a mark of his attaining salvation at that palce he asked Lord Siva to name that hill by his name. So this hill is called by his name as Vrushabadri.
Narayana Maharshi wanted to do Penance to see Lord Vishnu. He asked Lord Brahma to show a appropriate place where there won’t be any disturbenses for his Penance. Lord Brahma showed him a place where he did Penance for Lord Vishnu. Lord Vishnu was pleased by his prayers, appeared before Maharshi. Narayana Maharshi asked Lord Vishnu to give a boon so that the hill will be popular by his name. So this hill is called by his name as Narayanadri.
According to Bhavisyathara Puranam this is the place where Garuda brought Lord Vishnu from Vaikuntam. “VEM” means “sin” “KATA” means remove(harinchatam).This means all sins will be removed in presence of the god. So this hill is called as Venkatadri .