http://www.istanbul-city-guide.com/: The site offers Hagia Sophia - Istanbul ( Aya Sofya ) The Sultan Ahmed Mosque is famously known.. The Topkapi Palace Museum - I Dolmabahce Palace Museum - Istanbul Istanbul Archaeological Museum as places to visit.

http://www.lonelyplanet.com/worldguide/turkey/istanbul/: The site states : Byzantium, Constantinople, Istanbul: by any name it's glorious. Straddling the Bosphorus, its skyline studded with domes and minarets, Istanbul is one of the truly great romantic cities. Its history tracks back from Byzantium to Constantinople to its place at the head of the Ottoman Empire. Today it hums as Turkey's cultural heart and good-time capital. In this sprawling, continent-spanning city you can tramp the streets where crusaders and janissaries once marched; admire mosques that are the most sublime architectural expressions of Islamic piety; peer into the sultan's harem; and hunt for bargains in the Kapali Carsi (Grand Bazaar).