Caves and rockshelters are a key component of the archaeological record but are often regarded as natural places conveniently exploited by human communities. Archaeomorphological study shows however that they are not inert spaces but have frequently been modified by human action, sometimes in ways that imply a strong symbolic significance. In this paper the concept of 'am'enagement', the re-shaping of a material space or of elements within it, is applied to Chauvet Cave in France and Nawarla Gabarnmang rockshelter in Australia. Deep within Chauvet Cave, fallen blocks were moved into position to augment the natural structure known as The Cactus, while at Nawarla Gabarnmang, blocks were removed from the ceiling and supporting pillars removed and discarded down the talus slope. These are hence not 'natural' places, but modified and socially constructed.