Exposed during previous Soprintendenza excavations, SU 5505 are tufo slabs that are the continuation into Room 11 of tufo pavement 5321 (also 5485 in Room 9) on which 5318 was later constructed and against which (and maybe on top of?) floor associated with tufo prep 5489 may have been constructed. They paved a large, presumably open, area associated with the ramp from the lower to the second terrace.