Alexandria
Alexander's 331 BC double-harbour founder effect gave Alexandria 2,300 years of port dominance—now threatened by the rising sea that made it great.
Alexander the Great chose the site in 331 BC not for sentiment but for hydrology: a limestone ridge between Lake Mareotis and the Mediterranean created a natural double harbour, one sheltered from storms, the other facing open sea. That founder effect gave Alexandria two millennia of port dominance. The ancient Library held perhaps 400,000 scrolls—the world's first attempt at totalising knowledge, a network effect in papyrus. The Pharos Lighthouse, one of the Seven Wonders, was a costly signal visible for 50 kilometres, broadcasting safe harbour to every merchant vessel in the eastern Mediterranean.
Modern Alexandria stretches along 32 kilometres of coastline and holds roughly five million people. Egypt's second city handles about 60% of the nation's foreign trade through its western harbour and the adjacent Dekheila port. The city's industrial belt produces cement, textiles, and petrochemicals, but its economic metabolism has shifted: Alexandria now competes with Port Said and the Suez Canal Economic Zone for logistics investment, a competitive exclusion pressure that has eroded its historic monopoly.
The city exhibits a layered ecological succession visible in its archaeology. Greek columns underlie Roman baths; Coptic churches sit on pharaonic foundations; Ottoman mosques adjoin French-style boulevards. The Bibliotheca Alexandrina, opened in 2002, consciously echoes the ancient library—a path-dependent appeal to intellectual heritage as economic strategy. The city's Corniche seafront, built during the cosmopolitan era when Greeks, Italians, Jews, and Egyptians shared the city, recalls an era of gene flow that nationalist policies in the 1950s and 1960s largely terminated.
Alexandria faces an existential threat from rising sea levels. Studies estimate that a one-metre rise could displace over two million residents and submerge significant portions of the city's low-lying delta terrain. The organism that Alexander planted on a limestone ridge may discover that its greatest vulnerability is the same water that gave it life.