After some initial confusion over what were original beams or not I have found a definitive pictorial source of the original wood and chamber in question which includes the massif.
Source.
Here is an interesting pictorial going from one entrance to the other:
Overview
Northern Passage and Antechamber
Lower Chamber and Chimney
Connecting Tunnel
Horizontal Passage and Portcullises
Upper Chamber






Source.
Here is an interesting pictorial going from one entrance to the other:
Overview
Northern Passage and Antechamber
Lower Chamber and Chimney
Connecting Tunnel
Horizontal Passage and Portcullises
Upper Chamber