(I) Wealth began to pour into Istanbul as the Ottoman State spread westwards. (II) Further, the city had an influx of skilled craftsmen from the new territories of the empire. (III) Towards the end of the 17th century the Ottomans began to lose their technological advantage over Europe. (IV) Thus, the city, which had begun to fall into disrepair with the slow decline of the Byzantine Empire, began to return to its former glory. (V) This was helped by the works of the great architect Sinan.