This feature seems to consist of basalt paving stones (perhaps spoliated from adjacent road 6039), in secondary deposition, possibly intentionally reused/integrated into one of the late gravel surfaces (6078 or 6082).
Basalt paving stones on N-S roadway; tufo block north of via Gabina; rectilinear stone feature north of via Gabina between walls 6070 and 6056; three basalt stones south of 9003, between walls 6070 and 6056; gravel pavement north of via Gabina, between walls 6070 and 6033.
Rectilinear stone feature north of Via Gabina between walls 6070 and 6056 and adjacent features
photo from west
photo from south
photo from east