Upon closer inspection during the offseason in the preparation of the preliminary report, it is highly likely this wall belongs to the first phase of the complex, and represents the westernmost stretch of the retaining wall that divided the lower terrace from the middle terrace. It is built directly upon bedrock. As the retaining wall proceeded westward, it took a slight jog northward from the line of the eastern portion of the wall (represented by blocks 5482 and 5487). This jog took place at the L-shaped N-S aligned ashlar block in the corner of Room 21 (SU 5909): this block represents a southern continuation of wall 5765, and the depression that has been carved into it is the standard width of an ashlar block (.45m) and was cut to accommodate a perpendicular E-W block.

These ashlar blocks may be part of a wall from an earlier phase because they were cut into for the purpose of inserting other blocks using mortar. The blocks inserted into these ashlars may have served to support some type of bench or shelf. It is unlikely that the cuts were made when the ashlar blocks (5845) were constructed, as it would have been easier to use concrete for the wall rather than cutting into ashlars. The ashlar wall itself seems to have served to divide rooms 20 and 21.