In Assassin's Creed, Altaïr visits Masyaf to investigate the Order of Assassins.
Masyaf is the mountain settlement that serves as the Assassins' headquarters in the first Assassin's Creed game. Altaïr Ibn-La'Ahad returns there after missions, receives instructions from Al Mualim, and reports what he has learned about the targets assigned to him.
The location is also important because the game opens with Altaïr, Malik Al-Sayf, and Kadar Al-Sayf attempting to recover a powerful artifact from Solomon's Temple. After Altaïr breaks the brotherhood's code during that mission, he is punished and must rebuild his status by carrying out investigations and assassinations.
Masyaf is based on the real Syrian settlement of Masyaf, which was associated historically with the Nizari Ismailis. The game fictionalizes its history and presents the group as the Assassin Brotherhood. Players sometimes confuse Masyaf with the cities visited during the investigation missions, such as Damascus, Jerusalem, and Acre; those are mission destinations, while Masyaf is the brotherhood's home base in this story.