The Ruhr basin is probably the best-surveyed foreland basin of the Variscides. As a case study, the geological setting, the basin configuration, sedimentary processes, stratigraphy, and fossil content of the Ruhr Basin in Germany are described, which, during the Pennsylvanian, developed from a flysch basin to an overfilled molasse through. The sedimentary basin originally included the Aachen-South Limburg coalfields in the southwest and extended to the Osning transfer fault zone in the northeast over more than 200 km. Here, the foreland basin, which is oriented parallel to the orogenic front, interferes with the rift-type Lower Saxony basin, which parallels the WNW-ESE-directed Central European Shear Zone. The Ruhr basin is clearly asymmetric with the highest thickness of sediments near the orogen, where the pile of Pennsylvanian sediments reached up to 7 km. During the Mississippian, and until the Marsdenian (Namurian B), the Ruhr Basin was part of the Rhenohercynian marine flysch basin. Starting already within the uppermost Marsdenian, during the Yeadonian (Namurian C) and lower Westphalian deltaic sedimentation filled the basin with molasse-type sediments. Sedimentation was controlled by basin subsidence, the amount of sediment input, autocyclic processes within the deltas, and global changes of the sea level triggered by the Gondwana glaciation. The combination of these factors led to a cyclic and sequential succession of clastic sediments, including some 150 coal seams. Tropical to sub-tropical climate and high groundwater levels promoted the growth of forest swamps as a source of the seams. Marine ingressions were frequent in the older part of the succession, but their number decreased during the Westphalian. The Aegir marine band at the border between Duckmantian and Bolsovian is the youngest marine band within the Ruhr basin. The fossil record of the basin includes as well marine faunas as terrestrial elements, namely plants, but likewise insects, arthropods, and others. In the late Westphalian, a larger part of the Ruhr Basin was involved in the final stadium of the Variscan Orogeny. In contrast to the allochthonous, thrust-dominated parts of the Variscan front in Western Europe, where the progress of the orogenic front was buffered by the pre-variscan structure of the London-Brabant Massif, the Ruhr Basin is interpreted as an autochthonous foreland basin.