The northern outer apse.
Both of the oracle holes are visible here,
as is the porthole doorway to the intramural room.
Note the well preserved corbelling above the upright slabs of the apse wall, the
gradual in-curving of each
successive course serving to reduce the roof gap to be spanned. The
northern "calendar" stone and "slab altar"
of the inter-apse portal can be seen on the left.
Note the large slab lying in the foreground,
this slab has a hole pierced through it of corresponding size to
that piercing the pavement slab of the inter-apse doorway. Discovered by Ashby
(1), in his excavations
of 1908-11, he describes it as the lintel stone that once spanned the doorway above the
pavement hole, he
thought that the two holes may have been used to house the upper and lower
pivots of a door.
As the stone was broken and could
not be replaced in its original position, he had it placed
in the location shown above.
1. Ashby T., Bradley R.N., et al, Papers of the British School at Rome, VI, 1913.