“If one had but a single glance to give the world, one should gaze on Constantinople,” marveled Alphonse de Lamartine, the 19th-century French writer and politician. Sixteen centuries as the legendary capital of the Byzantine, Roman, and Ottoman Empires, Istanbul has long entranced the civilized world. The sole city to span two continents, it physically and metaphorically bridges the cultures and philosophies of Europe and Asia, Occident and Orient. Historically a tolerant melting pot — as the center of Christendom for over a millennium and Islam’s seat for another 500 years — it remains home to the Patriarchate of the Eastern Orthodox Church, Sephardic Jewish heritage sites, and legacies of numerous ethnic groups. It sits at the crossroads of human history, a sprawling 700-square-mile (1,812-square-kilometer) hilly metropolis studded with nearly 20,000 cultural sites from the sixth millennium B.C. to present day. Flanking 19 miles (30 kilometers) of the Bosporus strait between the Sea of Marmara and the Black Sea, it is a linchpin for trade routes in all directions. Though no longer a capital, Istanbul is the cosmopolitan heart of the Turkish Republic, its financial center and most populous city. The mushrooming population exceeds ten million, crowding cobbled-lane waterfront villages and glass-and-steel corporate districts, spirited premier soccer matches and haute couture boulevards. Byzantium, New Rome, Constantinople, Old Stamboul. Its name has changed, but the glory endures.