In Assassin's Creed Revelations, the modern city known as Constantinople in the game is Istanbul.
The game is set mainly in Constantinople during the early sixteenth century, when the city was the Ottoman capital. Ezio Auditore travels there to pursue keys connected with Altaïr's legacy and becomes involved with the local Assassin conflict. The districts shown in the game include areas on both sides of the Golden Horn.
Constantinople was the historical name commonly used for the city, while Istanbul is the modern name used today. The city officially became Istanbul in the twentieth century, long after the period depicted in the game. Revelations also includes a separate historical storyline set in Masyaf, linking Ezio's journey to Altaïr's earlier life.