Sentence:  Maccario, it was evident, did not care to take the risk of blundering upon a picket, and a man led them by twisting paths until at last the hacienda rose blackly before them. Appleby could see it dimly, a blur of shadowy buildings with the ridge of roof <WSD>parapet</WSD> alone cutting hard and sharp against the clearing sky. 
Meaning of the word marked with <WSD> tags:  Part of a perimeter that extends above the roof.