Given below are sentences with an error in each. The error is in one part of the sentence. Below each sentence are given the options containing the parts of the sentences. Choose the option which contains the error. Amid the heart of the bustling metropolis, amidst the towering skyscrapers that reached for the heavens with their glinting glass facades, a labyrinthine network of narrow alleyways and hidden courtyards existed, each bearing witness to the whispers of history and the stories of those who had tread upon their ancient cobblestones.