E-W running wall of grey tufo blocks, faced on exterior but roughly worked on interior. Abutted on S by basalt paving 4048 and tufo/ basalt paving 4041--seems to serve as N wall for these areas and possible S wall for a room bounded on N by wall 4007 and on W by E retaining wall of road 4023. Photographed and shot in in 2011 but to be photomodeled and more fully documented in 2012 when more fully exposed.