In Assassin's Creed Revelations, which older Assassin does Ezio seek in Constantinople?

In Assassin's Creed Revelations, Ezio seeks the legacy of Altaïr Ibn-La'Ahad while investigating the Masyaf keys in Constantinople. Altaïr is the protagonist of the original Assassin's Creed, while Ezio is the protagonist of the later story.

The game takes Ezio to Constantinople in the early sixteenth century, where he searches for five keys connected to Altaïr's former library at Masyaf. Each key reveals a memory from Altaïr's life, allowing the game to connect the two major Assassin protagonists.

Revelations therefore serves as both the conclusion of Ezio's trilogy and a continuation of Altaïr's arc. Desmond's modern-day storyline also appears through Animus sequences and the island of Animus. Constantinople is the game's principal setting, although Cappadocia and Masyaf are also visited during the campaign.