Sentence:  Within it a passage with what is described by Westropp as a <WSD>'murder hole</WSD>' on the roof just inside the doorway. This <WSD>'murder hole</WSD>' extends the width of the passage and is covered over by well fitting stone slabs. 
Meaning of the word marked with <WSD> tags:  (rare) A chamber above the entrance to a fortification where defenders hide and  shoot at invaders trapped in the entryway below.