The Assassin's Creed Brotherhood headquarters is located in Rome.
Assassin's Creed Brotherhood follows Ezio Auditore after the events of Assassin's Creed II. Its main historical setting is Rome, where the Borgia family and their allies control much of the city. Ezio works to weaken their power while rebuilding the local Assassin Brotherhood.
The headquarters is based at the Tiber Island hideout, a real island in the Tiber River. From there, Ezio recruits and trains new Assassins, sends them on missions across Europe, and coordinates the campaign against the Borgia. The game also lets players restore businesses and landmarks throughout Rome.
Florence and Venice are important settings in Assassin's Creed II, while Constantinople is the main setting of Assassin's Creed Revelations. Rome’s role is especially distinctive because the game focuses on rebuilding an organization rather than simply following Ezio as an isolated operative. Brotherhood also introduced the series’ first major multiplayer mode.