Strabo and Pliny both record that when the oracle of Apollo directed the Athenians and Megarians to found a new city in 657 BC, it told them to build "opposite to the blind." They understood this as a reference to Chalcedon — the settlement whose founders had inexplicably settled the Asian shore while the European promontory sat unclaimed. History has been unkind to Chalcedon's reputation in this regard, but the reality was more complicated. The Asian shore offered good anchorage in the sheltered bay at Fenerbahçe, a reliable stream the ancients called the Chalcis, and productive agricultural land. A fountain in the surrounding territory, Strabo dryly notes, contained small crocodiles. The settlement was no backwater: it built temples, including one to Apollo with its own oracle, and its territory stretched along the Anatolian coast of the Bosphorus as far as what is now Yoros Castle. It attracted philosophers, physicians, and sculptors. Herophilos, born here around the fourth century BC, became one of antiquity's greatest anatomists. The mineral chalcedony takes its name from this city.

Chalcedon's misfortune was geographic. Armies wishing to attack Constantinople from the east arrived first at Chalcedon's doorstep, and they usually helped themselves to whatever was useful before crossing the water. The Persians under Otanes captured the city in the sixth century BC. Darius the Great used Chalcedonian territory as the eastern anchor of his bridge of boats across the Bosphorus in 512 BC, built for his Scythian campaign. Mithridates of Pontus attacked the city savagely; three thousand Romans sheltering there were killed and sixty ships were captured. In the seventh century AD, Persian forces under Chosroes II camped at Chalcedon for the better part of a decade while besieging Constantinople. Arab forces under Yazid followed. The Fourth Crusade in 1204 brought further devastation. Even after the city passed definitively to the Ottomans under Orhan Gazi — a century before they took Constantinople — it continued to be stripped for building materials. Byzantine emperors and Ottoman sultans alike quarried Chalcedon's stones for the monuments they raised across the water. The city of the blind became a quarry for the city of the sighted.

In October 451 AD, some five to six hundred bishops gathered in Chalcedon — the largest church council the world had yet seen — to settle a question that had been tearing the Christian world apart: what was the precise nature of Jesus Christ? Was he divine, human, or some inseparable blending of both? The Council of Chalcedon, the Fourth Ecumenical Council of the Christian church, produced its answer: Christ has two complete natures, divine and human, united in one person without confusion, change, division, or separation. The formula was precise, philosophically sophisticated, and deeply controversial. The Oriental Orthodox churches — including the Coptic, Ethiopian, Armenian, and Syriac traditions — rejected it, holding instead that Christ's divine and human natures are united in a single nature. This schism has never been healed. Well over a hundred million Christians today belong to Oriental Orthodox communions whose separation from Rome and Constantinople traces directly to the fields and council halls of this Asian-shore city. The cathedral where the bishops deliberated was consecrated to Saint Euphemia, a local martyr of the early fourth century, whose relics were kept there. Her feast is still observed.

Almost nothing of ancient Chalcedon stands above ground in modern Kadıköy. The Fikirtepe mound nearby has yielded Chalcolithic remains dating back as far as 5500 BC, evidence of continuous human habitation going back seven thousand years before the Megarian colonists arrived. Artifacts uncovered at Altıyol and other excavation sites in the neighborhood are now displayed at the Istanbul Archaeological Museum. The Maiden's Tower — that iconic lighthouse rising from a tiny islet in the Bosphorus — is sometimes associated with Chalcedon's waters. Julian the Apostate convened a tribunal here in 361 AD to try his political enemies. Belisarius, the great general of Justinian's campaigns, likely retired to his estate of Rufinianae in the Chalcedonian countryside. The Greek Orthodox Metropolis of Chalcedon still exists, holding the third-ranking position within the Ecumenical Patriarchate of Constantinople — a titular dignity attached to a place whose ancient stones are long since incorporated into the mosques and palaces across the water.

Step off the ferry from the European shore and you are in Kadıköy: loud, colorful, crowded with cafés and fish stalls, bookshops and street musicians. The Asian shore no longer feels like second choice. This is a neighborhood of Istanbul's young creative class, and on weekend mornings the market along the waterfront draws crowds that would have impressed any ancient merchant. No column drums protrude from the pavements, no inscription warns of the council's decrees. But the name of this place — carried in the Greek Calchedon and Latinized as Chalcedon — echoes through the ages in every theological argument about Christ's nature, in the word for a waxy blue-white mineral prized by lapidaries, and in the unresolved divisions of Christian communions that began here in 451 and continue today. Megabazus was wrong. The city of the blind saw quite a lot.