Rivers convey ideas as well as merchandise, Victor Hugo observed during his Rhineland tour of 1838–9. Though essentially a geographical expression, the ‘Rhineland’ encompasses a distinct if diverse historico-cultural space, albeit one whose precise limits have varied over time. Like many, Hugo was especially captivated by the central stretch of the river, the Middle Rhine, which flows between Bingen and Bonn. Enclosed by rocky hills, this segment presents the familiar panorama of ruined castles and vineyards clinging precariously to terraces. Less known are the upper reaches of the Rhine, between Basel and Mainz, where the wide and shallow river valley is bordered by the Black Forest in the east and Vosges in the west, and the lower reaches north of Bonn, where the Rhine undergoes its second metamorphosis as it merges with the great northern European plain.

The Rhine has moulded its surrounding landscape and shaped the civilisation that developed along its banks over the last two millennia. Rome, whose legions stood on its banks for the first four centuries after Christ, left its indelible mark in the form of cities – notably, Moguntiacum (Mainz), Confluentia (Koblenz), Colonia Agrippina (Cologne) and Augusta Treverorum (Trier) – and the Church. These survived Roman rule and the subsequent Frankish epoch that closed with the Carolingian Empire's collapse in the ninth century. They survived over the following centuries, within the framework of the Holy Roman Empire. Architecturally, Romanesque abbeys and cathedrals attest to the medieval Church's vitality.