First, I would just like to say that you are reading a book by a Spanish author who lived 400 years ago. Even most native speakers of English would have great difficulty wading through this translation of his work. If you are reading such books to learn English, you are really doing it the hard way!
To answer your question, I believe the author is saying a hope remains that the towers of the city may rise again, though not for the reasons for which they were originally built (the defense of the city).
Student or Learner