This address is the fictional location of Dr. Stephen Strange's lair, the Sanctum Sanctorum. The three-story brownstone in Greenwich Village is home to Strange and his manservant, Wong, as well part-time residents Clea (Strange's lover/apprentice) and apprentice sorcerer Rintrah.
The building has served as headquarters for both the New Avengers and the Defenders. The second floor are sleeping quarters for Strange, Wong, and guests. The third floor is the Sanctum Sanctorum specifically- Dr. Strange's occult library housing the Book of Vishanti and the Orb of Agamotto.
The Sanctum Sanctorum first appeared with Doctor Strange in his debut in Strange Tales #110 (July 1963).

