Sentence:  We even went down into the cellars, where was a vast vault filled with coal. "This puts to shame the <WSD>subfenestral</WSD> carbonaria of your alma mater." Every university-man knows how the coal-porter brings his sack on his shoulder, and empties the load into the hollowed-out window-seat; "Forsan et haec olim meminisse juvabit." 
Meaning of the word marked with <WSD> tags:  Beneath a window.