Sentence:  “One evening,” she went on, “while Madame Orio was fast asleep in her little <WSD>belvedere</WSD> (it being the good old lady's habit to repair there to rest after a bottle or two of red Padua wine), Manette and Marton left the widow's house noiselessly in the Campo San Zobenigo, and made their way running towards the Piazza of St. Mark's.” 
Meaning of the word marked with <WSD> tags:  A turret or other raised structure offering a pleasant view of the surrounding area.