SU 5453 is a pier comprised of three very large ashlars, of increasing size as they reach the ground, stacked on top of one another in the south east corner of room 15, south of red tufo wall 5417. The sheer depth and size, along with its alignment with walls 5412 and 5460 suggest that the pier is in situ (though not in its original height) belonging to an early phase with course tufo walls 5417 and 5460 against which cement features (ie 5530, 5432) and later re-used blocks (ie 5452) were constructed.