Istanbul is one of the greatest cities the world has ever know. Inhabited for at least 8,000 years, it was capital of two of the world's most powerful empires -- those of the Byzantines and the Ottomans -- and its every stone is steeped in history. The highlights are easy; you can cover the major attractions in the first couple of days. But after that, the choice can be overwhelming, especially as this ancient city is reinventing itself once more as a modern centre for nightlife, food and shopping. The only answer is to come back again -- and again. If you do, this endlessly fascinating city will certainly reward you.