New York Sanctum is a fictional location in the Marvel Cinematic Universe. It is a New York brownstone on 117A Bleecker Street in Lower Manhattan, Greenwich Village, and one of three bases for the Masters of the Mystic Arts to protect the world from mystic threats and likewise to store and secure mystic items, such as the Cloak of Levitation.
After Daniel Drumm was killed by the Zealots, Doctor Strange moved in as its guardian, along with Wong. When Doctor Strange joined Tony Stark and fought Thanos, he became one of the many casualties in Thanos using all the Infinity Stones to reduce the galaxy's population, leaving Wong, a survivor, in charge.
The Avengers used the Quantum Realm to go back in time to retrieve the Infinity Stones, which had been destroyed in the present by Thanos. Bruce Banner went to the New York Sanctum to retrieve the Time Stone, but not before convincing the Ancient One to essentially "loan" it to him.