In Assassin's Creed, Altaïr visits Damascus first after returning from Masyaf.
The 2007 game sends Altaïr Ibn-La'Ahad to three major cities during his missions: Damascus, Acre, and Jerusalem. Damascus is the first of these destinations after the opening sequence in which Altaïr's failure at Solomon's Temple leads to his demotion by Al Mualim, the leader of the Levantine Assassins.
Damascus is presented as a large urban environment divided into districts, including the poorer Poor District, the Middle District, and the wealthy Rich District. Altaïr gathers information there before pursuing targets connected to the game's larger conspiracy.
The order of cities can be confused with later missions, because Acre and Jerusalem also become important locations very early in the story. The game's fictional events are set during the Third Crusade in 1191, while the real Damascus was a major city in the medieval Islamic world. The first city Altaïr visits is therefore Damascus, not the Assassin headquarters of Masyaf.