Commons B-01

, also named Commons Blue, was a United Nations Space Command commons module aboard Cairo Station. It consisted of a standard-sized rectangular room, with "islands" regularly spaced to the edges of the room. Security B-01 overlooked Commons B-01.

During the First Battle of Earth, Covenant boarders invaded the module, pushing back Marines to the far side of the room, pinning them down by overlapping fields of fire from Plasma Cannons on the "islands", along with Grunts and Elites. However, they were repulsed by SPARTAN-117.