Structure D lies in the centre of the trench.
It is a fairly small structure, apparently a subterranean, or at least sunken, building that was constructed within the interior of Structure A, either at the time that Structure A was being in-filled with rubble or in the period after the rubble went in.
This structure has apparently been investigated before, in the fairly recent past, if the modern china and rusty iron fittings that we encountered are anything to go by.
Structure D was again constructed in a combination of coursed masonry and upright slabs. A narrow passage leading off of the main “chamber” appears to be the blocked-off entrance passage to what has possibly been a slab-roofed building at one time.
At the moment, this structure appears to be a souterrain constructed in the ruins, or rather back-fill, of Structure A, possibly in a similar manner to a couple of other such late Orcadian souterrains excavated at The Howe, and the Bu, (both near Stromness), respectively.
The further excavation of the interior deposits of Structure A this year should enable the team to examine this unusually placed “souterrain” in some more detail.