In the original Assassin's Creed, Masyaf serves as the Assassin Brotherhood's headquarters under Al Mualim.
Masyaf is a fortified mountain settlement in modern-day Syria. In the game's historical storyline, it is the home of the Levantine Brotherhood and the base from which Altaïr Ibn-La'Ahad receives missions. The settlement's elevated position and defensive walls make it an important visual symbol of the Assassins' hidden organization.
Players sometimes confuse Masyaf with the three major cities visited during the game: Damascus, Acre, and Jerusalem. Those cities are mission locations, while Masyaf is the Brotherhood's headquarters and training center. The game also opens and closes important parts of Altaïr's story there.
Masyaf is based on a real Syrian town associated with the medieval Nizari Ismaili state. Assassin's Creed uses historical names and settings while combining them with its fictional conflict between Assassins and Templars.