Complex sentence: The position is surprising as it would have been almost above the quarters of the châtelain and it is possible that the structure was originally a bartizan which was converted into a gardrobe when the upper floors were used as a prison.
Split into simpler sentences: The position is a little surprising as it would have been almost above the quarters of the châtelain. It is possible that the structure was originally a bartizan and was converted into a gardrobe when the upper floors were used as a prison.