See interpretation of the associated tile structure 5577.
Opus mixtum wall running north-south in NW corner of Room 17 (5744), Concrete superstructure on top of tiles 5577 (5745), Single tufo block west of wall 5744 (5746), Tile floor at W limit of room 17 (5577), Cluster of concrete and broken tufo blocks west of 5575 (5747), and Opus mixtum wall S of room 17 (5575)