The fertile lowland region known as the Cologne Bight (Kölner Bucht) encompasses a variety of landscapes that have proved quite amenable to human habitation. A terraced lowland area along the Rhine River’s western shore, it radiates in a northwesterly arc from Königswinter in the south to Aachen in the west and Krefeld in the north. The terrace carved most deeply by the glacial evolution of the Rhine extends some ten kilometers inland from the river and contains ancestral debris from the Alps, Eifel, Hunsrück, and Westerwald mountains. Throughout the bight, sand and gravel accumulated wherever the river's ancient branches flowed fastest to the North Sea, whereas clay was left behind wherever they meandered.

The bottom terrace nearest the modern Rhine River has fed innumerable generations of Cologne's denizens through a fruitful combination of its sandy clay loam deposits with the bight's mild climate. The middle and top terraces located along the arc from Geilenkirchen to Erkelenz, Odenkirchen, and Gerresheim also produced exceptionally fruitful farmland, especially in the flood plains of nearby Jülich, Zülpich, and Euskirchen along the rivers Erft and Rur (Roer). The south and southwest reaches of this rich alluvial lowland expanse was complemented by the Münstereifel mountains and southern Rhineland Massif, which provided lead and silver ore, coal for iron smelting, clay for pottery and glass production, and slate, basalt, and trachyte for roads and public buildings. Only quality limestone was lacking and so was imported from the upper Mosel River valley. The environmental assets so critical to Cologne's medieval economy thus had a very ancient pedigree.

The eastern shore of the Rhine River by contrast (known as the Bergisches Land) possessed only a narrow strip of rich loamy soil along the riverside’s bottom terrace, because the last Ice Age left deep deposits of heavy sand and sharply carved valleys throughout the middle terrace of the region. Instead of agriculture, therefore, this area contained extensive forests, which would prove invaluable as a wood and wood coal reserve once the left bank of the Rhine was substantially cleared for farming.

The oldest surviving evidence to date of human habitation in Cologne’s environs dates back to around 100,000 B.C., in the finely grained quartzite stone core (Kernstein) from Dellbrück and hand axe from Königsforst/ Porz-Heumar.