- "I don't know what you've heard about this place, but there will be a lot here to show you that I know you're going to love. Lots of history."
- ―William Miles to Shaun Hastings.[src]
The Assassin headquarters is the main base of the Assassin Order, and the meeting place for its highest-ranking members. Aside from being located in the United States, not much was known about the facility, though in an e-mail to Shaun Hastings, William Miles explained that the headquarters had "lots of history."
It was from here that William Miles coordinated with the Assassins across the globe, though others at the headquarters aided him in research as well. For investigations into the status of the different teams, William often stated that "headquarters [was] looking into it."
The location was evidently secure, as William mentioned that Shaun's Assassin team (which included Desmond Miles, Lucy Stillman, and Rebecca Crane) would be traveling to the headquarters once they had secured the Apple of Eden.