Doctor Strange has one of the weirdest houses in the entire Marvel Universe. Called the Sanctum Sanctorum, this three-story townhouse located at 177A Bleecker Street in New York’s Greenwich Village stores many of Strange’s mystical artifacts and is a labyrinth of rooms - some of which exist in different dimensions. In the MCU, the New York Sanctum is said to be one of three such buildings (with the others being in Hong Kong and London) that form a protective barrier around the world, shielding it from other-dimensional threats.
In the comics, however, the Sanctum has a much weirder origin and history. A focal point for supernatural energies, the house and its grounds had many unusual owners even before Doctor Strange took up residence, deliberately drawing on the energies of an existing place of power.
In Doctor Strange (2015) #2, Strange offers a short history of his house. Long before it was built, the land was a popular destination for shamans of the Wappinger tribe on vision quests. Later, the land became a mass grave or “Potter’s field” for paupers - most of them inmates from New York’s first prison. Once the house was built, it had several bizarre residents who used it for multiple oddball purposes. One Puritan witchfinder took up residence in the house and tortured immigrants in the basement. Later, some nuns attempted to turn it into a nunnery but failed. Possibly sensing that the house was better suited for less holy purposes, other residents decided to use it as a secret satanic supper club and a bacchanalian speakeasy or illegal bar. Others residents may have sensed the house’s mystical nature, since both beatniks and street mystics have used the Sanctum… as a flophouse.
Notably, the Sanctum Sanctorum has been burned to the ground repeatedly (even before Strange took up residence) only to be rebuilt multiple times. No one can state definitively who the original builder or later architects were, and even Strange has noted that it sometimes feels that “the place keeps growing back on its own.” Thanks to the building’s troubled history, Doctor Strange got the place for practically nothing when he moved to Greenwich, since nobody wanted to move into a place that was supposedly haunted. Fortunately, Strange (who can confirm the place really is haunted) has no problem with ghosts or spirits, provided they behave themselves. However, since Strange bought the place under his own name (and did not inherit the Sanctum from Kamar-Taj as he did in the MCU movie), he must pay rent on the place regularly.
The additions to the Sanctum Sanctorum's history were part of writer Jason Aaron and artist Chris Bachalo's attempts to emphasize the "Strange" elements of Marvel's Sorcerer Supreme, treating him as less of a conventional superhero and more of an expert in the genuinely weird excesses of the Marvel Universe. Humorously, several demons have become convinced that Strange moved into the Sanctum Sanctorum because it contains powerful magical gates. Although the house does have a powerful connection to magic, Doctor Strange later confirmed that he only moved to Greenwich Village because he likes the people in his neighborhood. He further revealed that he has enchanted the house so it can move anywhere on Earth (and even to the moon), yet chooses to let the house remain on its original grounds where it can continue to add to its own eccentric history.