Located at 177a Bleecker St. in Greenwich Village, the Sanctum Sanctorum serves as a multiversal nexus point as well as the home of Doctor Stephen Strange. It also served as the headquarters for the Defenders. One particular battle that took place was during the Siege of Darkness where he let the team known as the Midnight Sons hide and rest here, but it was later broken into and attacked by the Lilin, and as a means of defense the sanctum later got destroyed accidentally by Doctor Strange himself. But later on the Sanctum would be rebuilt back to its normal status. When the new incarnation of the Avengers was created, right after the events of Civil War, Luke Cage and the "real" Avengers are allowed to live in the Sanctum Sanctorum. Those allowed to live inside were hidden by complex magical spells. A more prosaic way of hiding was a banner on the outside of the building indicating a 'Starbucks' was soon to be built on the spot. Despite the precautions, many battles were fought there. When Dark Reign struck, Doctor Strange vanished, and the "New" Avengers abandoned "their" home.
Strange was forced to abandon his home after losing his title of Sorcerer Supreme. Luke Cage invited him to the Avengers Mansion. After regaining his title, Strange moved back to his Sanctum. As indicated in the Deadpool 2014 series, it cannot be found if Strange wishes it, even by people who were welcome there before.
The story about the origin of this house is told in Doctor Strange: From the Marvel Vault.
Video Game Appearance
Marvel: Avengers Alliance
The Sanctum Sanctorum is a stage in the game. Though the place can be seen in the map, it is not accessible unless a threat is present in the building.
The Sanctum also appears in 'Marvel Ultimate Alliance' as a safe zone for the heroes. It is possible to visit many rooms.