Above your head is the central boss with the lamb and flag.  It is fixed at the bottom of the king post which rises to the apex of the roof.  Now look for this boss and the king post in the model.

The king post is constructed from three huge oak trees spliced together.  Its weight is held by the whole structure, primarily supported on four horizontal beams crossing in the centre (where the human figure is standing in the model).  Eight queen posts and eight pendant posts terminate at the base with the ring of sixteen bosses visible above your head.  Almost every timbre is numbered, which indicates that the roof was pre-made at ground level, then dismantled and reassembled in situ. *

*From an information board a York Minster.