This structure is a concrete wall with facing that is difficult to identify. Together with SU 8233, which is bound to wall 8120, it forms part of a structure, probably a wall, that sits atop arch 8237. This suggests that room I-11 is a substructure, which has been tentatively identified as a praefurnium or cistern. It appears that this sector of the complex consisted of two floors during its initial phase of construction.