In Assassin's Creed: Revelations, which city does Ezio Auditore primarily explore?

In Assassin's Creed: Revelations, Ezio Auditore primarily explores Constantinople.

The game is set in the early 16th century, when Constantinople was the capital of the Ottoman Empire. Ezio travels there while searching for Altaïr's legacy and the keys connected to the ancient Masyaf fortress.

The city is divided into districts influenced by its historical neighborhoods, and the story features Ottoman characters including Prince Suleiman, the future Sultan Suleiman the Magnificent. Ezio also works alongside Yusuf Tazim, leader of the Constantinople Assassins.

Constantinople was officially renamed Istanbul in the Republican period of the 20th century, but the historical city was still commonly called Constantinople during the game's setting. That distinction explains why the game title and question use Constantinople rather than the modern name Istanbul.