The Silversun Strip provides another main hub area on the Citadel where Shepard can interact with current and former squad members. Shepard will receive e-mails from allies asking the Commander to wait for them somewhere in the area, or to invite them up to the Personal Apartment. These encounters are dependent upon the ally in question's own mission being completed, such as Grunt asking to meet Shepard some time after the Attican Traverse: Krogan Team mission has been completed.
Notable NPCs found in this area include Francis Kitt talking to an admirer about his new production of Macbeth with a krogan lead and a pyjak, and an out-of-work elcor actor who quotes from Hamlet if interacted with.
In Castle Arcade there is a powered-down Towers of Hanoi game. If Shepard interacts with it the Commander will say 'Towers of Hanoi? I don't think so.' This is mostly likely a reference to BioWare's use of the puzzle in several games, including in Noveria: Reactor Repair in the original Mass Effect.