Surrounded by water on three sides, the city of Istanbul straddles Europe and Asia and is one of the largest urban centres in the world. It is a global city whose layers of archaeology and architecture have evolved over centuries in the historic political and religious centre of the eastern Mediterranean. The enviable site was first settled in the seventh-century BCE by Greek fishermen. In 330 CE, the Emperor Constantine chose the trading centre, then known as Byzantium, as his new capital of the eastern Roman Empire. Renamed Constantinople, the holiest and most magnificent city in eastern Christendom was graced with the great domed basilica of Aya Sofya, the ‘Church of Holy Wisdom’. Completed in 537 CE, it was the world’s largest cathedral and an architectural inspiration for nearly a thousand years. The coveted city, surrounded by water on three sides, was all but destitute in 1453 when the Ottoman sultan Mehmet II, ‘the Conqueror’ (r. 1451- 1481), stormed its ancient defence walls. After taking control from the final Byzantine emperor, he began the process of transforming the stricken city into the third and last Ottoman capital, Istanbul, with one of the most distinctive skylines in the world. Modern Istanbul is a booming metropolis, with fascinating street life, beguiling bazaars, lively restaurants and internationally-recognised and fast-evolving architecture, design and contemporary art.