The Garbha Gruha or sanctum is where the main idol of Lord Sri Venkateswara resides.
The Lord's image is in Sthanaka or standing pose. The Lord is standing on a high lotus pedestal. The height of the Lord has never been recorded, but cannot be less than nine feet from the tip of the 'mukutam' i.e., the crown to the bottom of the lotus pedestal. This can be seen clearly on Friday when 'abhishekam' is done after removing all the gold 'kavachas' (ornaments of this figure). The priest performing the worship, about five feet tall, standing on a stool, two and a half feet high, will not be able to perform 'abhishekam' on the Lord's mukuta unless a priest assists him from behind the idol. Keeping in view this fact that the pedestal on which the Lord stands, is itself below the floor in the sanctum sanctorum, the Lord's figure from tip of the crown to the vase of the lotus pedestal, must measure between nine and ten feet.
According to tradition, the idol of the Lord is manifested in Saligram Sila. The idol of the Lord is liberally anointed frequently with civet or 'punugu' oil; this application of oil makes the idol dark in colour and does not enable us to make an accurate assessment of the material of the image. The material of the idol could be granite or the red igneous rock.
The Lord's majestic beauty is best seen at the time of the Friday Abhishekam when the jewels and other paraphernalia do not cover our view of Him in His celestial glory. It is at this time that we see the eyes of the Lord in the 'sama drishti pose' showering divine grace. The eyes neither look up nor downwards, but straight into devotees' eyes. The Lord wears a ‘mukuta’ or crown which is more than 20 inches high. The Lord's figure is richly adorned with flowing locks of hair or jata juta and some of these locks of curly hair rest on his shoulders.
The nose is delicately carved, neither prominent nor flat, and the mouth of the Lord is also exquisitely shaped. According to Pratima Mana Lakshanam the mouth should be made slightly smiling, pleasant and possessed of all good signs. The chin and the ears are carved proportionately, the ears wearing beautiful ear ornaments.
The chest of the Lord is magnificent in cut and size and should, if measured, be between 36 to 40 inches in width, while the waist would be between 24 to 27 inches. The neck is conch like and the body in the posture of a lion and exquisitely shaped. The belly is also beautifully modeled.
The Lord's image has four arms, the upper two being carved to hold the chakram and the conch ( the chakram and the conch are not integral parts of the main idol). The upper right arm holds the Sudarshana Chakra and the upper left arm holds the Panchajanya. The lower right hand of the Lord is in the Varada hasta pose, while the lower left hand is in the Katyavalambita pose. Actually the fingers of the left hand rest on the left thigh, with the thumb of the hand almost parallel to the waist line.
While the idol itself is not exactly standing in the tribhang pose, as in the case of Sri Rama’s idol, the near and below the waist has taken a slight tilt to the left and the knees themselves are bent and open slightly outwards, giving the idols peculiar grace and charm.
Mother Laxmi is carved on the right chest of the Lord in the sitting pose and is an integral part of the mula murthi (main idol).
The yajnopavitam and a set of four necklaces or ornaments of the neck which can be clearly made out on the idol. The arms have armlets with finger-like projection which appear to be Nagabhushanams or Cobra ornaments. A cobra is also said to be coiled around the Lord's right arm. The figure is depicted as wearing a dhoti from the waist downwards, while the upper portion is not covered by any dress or vastram. The nipples of the Lord on his chest are button like and are prominent. There is however a katibandham or waistband and this waistband is about 2 inches thick.
The legs and feet of the Lord are beautifully shaped, strong and lissome. As indicated earlier, both the knees are bent and open slightly outward, giving the stately figure charm and grace, that words cannot adequately describe. The feet are models of perfection and have ornaments near the anklets.
The Lord's image has marks on the shoulders resembling 'scars made by the constant wearing of the bow and a pack of arrows'.
The Image resembles Bodhisattva Image.
During the reign of the Vijayanagara king, Yadava Raya, in the thirteenth century, the Ananda Nilaya Divya Vimana was covered with gilt copper plates and surmounted with a golden vase.
Pilgrims are not allowed to enter the Garbha Gruha (beyond Kurasekara path).