This is a large, deep negative feature in the middle of the pavement of the piazza (7044) of uncertain function, but most likely related to the disposal or procurement of water (i.e. either a drainage shaft or a cistern/well). Hopefully future seasons of fieldwork can further clarify its function, as well as the phase to which it belongs.
View from south (uncleaned, mostly modern safety precautions visible)
View from west (uncleaned, mostly modern safety precautions visible)