In the first Assassin's Creed game, Masyaf serves as Altaïr Ibn-La'Ahad's headquarters.
Masyaf is a fortified mountain settlement in modern-day Syria and the home of the Assassin Brotherhood during the game's medieval storyline. Altaïr returns there between missions to receive instructions, report to Al Mualim, and advance through the Brotherhood's ranks. The location is also the setting for the game's opening sequence, where Altaïr's failed assault on Solomon's Temple leads to his demotion.
The game presents Masyaf as both a practical base and a symbol of Assassin authority. Its elevation and fortress-like design distinguish it from the major cities Altaïr visits, including Jerusalem, Acre, and Damascus. Those cities are mission locations, not his permanent headquarters.
Masyaf also has a real historical connection to the medieval Nizari Ismaili community, often associated in popular culture with the Assassins. The game's fictional Brotherhood draws inspiration from that history while adding its own characters, rituals, and mythology.