Which city is the headquarters of the Assassins in Assassin's Creed Revelations?

Constantinople is the headquarters of the Assassins in Assassin's Creed Revelations.

The game follows Ezio Auditore as he travels to Constantinople, the capital of the Byzantine Empire, in search of Altaïr Ibn-La'Ahad's lost Masyaf keys. The city serves as the main hub for the story and is divided into districts that Ezio explores, investigates, and helps reclaim from Templar influence.

Revelations was released in 2011 and is set mainly in the early sixteenth century. Its historical plot includes the Ottoman succession struggle involving Prince Suleiman, who later became Sultan Suleiman the Magnificent. Ezio also encounters the Ottoman Assassin Yusuf Tazim, who helps him navigate the city.

The modern framing story returns to Desmond Miles, while playable sequences set in Masyaf and Cappadocia broaden the narrative beyond Constantinople. The city is now commonly called Istanbul, but the game uses its historical name.