The air temple sanctuaries are large, ancient chambers located in the Southern and Northern Air Temples that were originally intended to be opened solely through airbending. They were considered important to the Air Nomads as a place where knowledge of the Avatar and the Avatar's previous incarnations were kept. Prior to their restoration by the Air Acolytes, entry to the sanctuaries was restricted to the Avatar and the Council of Elders.
Monk Gyatso, Aang's mentor, confided in Aang that when he was ready, he would meet someone special inside the air temple sanctuary who would guide him on his Avatar journey. However, Aang fled the Southern Air Temple before this could occur.
A century later, Aang visited the Southern Air Temple with Katara and Sokka, and, remembering what Gyatso had told him, Aang opened the sanctuary doors with airbending. Instead of finding a master to teach him, he came across a long line with statues of previous Avatars. It was here that he saw his future pet lemur, Momo, for the first time, watching him from the doorway behind them. Aang and Sokka raced to catch Momo, with Aang wanting to befriend him and Sokka wanting to eat him. The chase led Aang to accidentally stumble upon Gyatso's corpse, and his rage and grief caused him to enter the Avatar State. While in the Avatar State, the eyes of the statues in the sanctuary began to glow. When Aang calmed down, he and his friends returned to the sanctuary. Momo brought Sokka food as a gesture of friendship and officially joined Team Avatar later.
Aang and his friends came across another one of these sanctuaries when they traveled to the Northern Air Temple. At first, Aang was unhappy with the changes the mechanist made to the temple, but after he saw how spirited the people who lived there were, he decided to open the sanctuary doors for Teo. When he opened them, however, he found nothing but Fire Nation weaponry.
After Team Avatar and their allies had launched an unsuccessful attack on the Fire Nation, the youngsters of the group were forced to flee and took refuge in the Western Air Temple. While there, The Duke, Haru, and Teo set out exploring, the latter remarking that he wondered if the temple had a sanctuary as well.
Tenzin's family visited the Southern Air Temple to start their vacation. Once there, Tenzin brought his children to its sanctuary. Jinora was in awe upon seeing the statues of the past Avatars, and more so upon seeing that of her grandfather. Ikki and Meelo were not paying attention and decided to race around the room on air scooters. The race was cut short when Meelo crashed to a statue, knocking it over and obliterating it. Shortly after this, Jinora, while looking at Aang's statue, felt a presence. However, she turned around to only find more statues. In the middle of the night, she returned to the statue room and made her way up the chamber. She took notice of an odd statue, carved from wood rather than stone. Intrigued by it, Jinora stared at the statue, unaware of the Avatar it was meant to depict. While admiring it, the statue began to glow concurrently with Korra opening the spirit portal at the South Pole.
The sanctuary was visited a few days later by Bumi, who spoke to Aang's statue and expressed his regret for not being born an airbender like his father had hoped. He went on to assure his father's statue that he had done his best to protect the world and uphold his legacy. Kya overheard her brother and assured him this was the case before giving him a quick hug.
The sanctuary in the Southern Air Temple consists of a tall, circular chamber where a statue of every Avatar preceding Korra encircles the room in a large swirl, corresponding to the Air Nomad insignia. Also referred to as the statue room, it is considered to be the most sacred place in the entire Southern Air Temple. The sanctuary door is large and made of thick wood and can be opened only with airbending. The statues of all the Avatars are lined up according to the Avatar Cycle. In the past, the monks held group meditation sessions in the sanctuary as a means of further deepening the spirituality of the Air Nomads.
Located inside the air temple, this great hall was originally built as a spiritual place, and only a master airbender could open the door to the sanctum. Because of this, Aang thought it was the only part of the temple that was untouched. However, as it turns out, the mechanist ingeniously used physics and clever mechanics to open it. Until he was caught by Team Avatar, the mechanist used the sanctuary as his secret weapons laboratory.
- The Fire Temple on Crescent Island also had a sanctuary door, and similar to how the air sanctuary door could only be opened with airbending, it could only be opened with firebending.
- Of the named Avatars preceding Aang, Avatar Roku's statue was the only one shown to be in its proper place in the circular arrangement within the Southern Air Temple's sanctuary, as Kyoshi's statue was not next to his, and the other confirmed Avatars were not shown at all. However, this has been fixed by 171 AG, following the restoration of the sanctuaries by the Air Acolytes.