Masyaf is Altaïr's birthplace in Assassin's Creed.
Altaïr Ibn-La'Ahad is born in 1165 in Masyaf, a mountain settlement that serves as the headquarters of the Levantine Assassins. The location is in present-day Syria and is also the base from which Altaïr receives missions during the original game.
The first Assassin's Creed takes place during the Third Crusade and includes Masyaf alongside the major cities of Jerusalem, Damascus, and Acre. These cities are distinct mission locations, so identifying Altaïr's birthplace requires separating his home base from the cities he visits.
Masyaf's importance extends beyond its geography. The fortress represents the authority of the Assassin leader Al Mualim and becomes central to the game's opening and ending. Altaïr later returns there after carrying out missions across the region.