This feature was a later addition as it is built from rubble made up of basalt likely taken from nearby roads together with sherds of pottery and tile. The linear shape indicates that it was likely a room's limit that was originally topped with a concrete wall. It might therefore be associated with the nearby concrete wall SU 5416, which is parallel to its N-S side on the other (i.e. western) side of threshold SU 5451.
NS ashlar wall in Room 15