This paper presents new data on the spatial organization of mound-builder groups in the India Muerta wetlands, Uruguay. This area presents the beginning of land architecture in the region (ca. 4800–5000 years BP), associated with more arid climate. This construction tradition continues and intensifies, mainly from ca 3000 years BP, from the establishment of warmer and damper conditions. New sources of information and geospatial technologies have made it possible to locate mound sites with greater precision, as well as to analyze settlement patterns. Indigenous communities occupied areas of hills, plains and wetlands, showing differences but also regularities in spatial organization in each area. In the whole area, earthen mound complexes form groups of different orders, from regional to domestic units, configured by mounds, negative structures and limited spaces. The location of the mounds is primarily in dry areas, known locally as islands, which are prominent in the landscape during floods in this wetland-dominated environment. Through this analysis of the landscape, this work delves into the underlying logic of the social construction of the territory. The results achieved in this paper are consistent with previous research suggesting planned occupation associated with villages integrated within broader regional systems.

We analyzed, from a cultural astronomy perspective, the relationship between the orientations of five mound sites and different astronomical events in the lowland region of Uruguay. We found significant relationships between the orientations of the mounds and the Southern Cross/Milky Way and the full Moon during the winter solstice ca. 3000 years BP. These relationships, meanings and senses to different native peoples of South America were explored from the literature of travelers’ and naturalists’ chronicles, alongside the ethnohistorical, ethnographic and archaeological literature. In particular, we highlighted the link among those peoples of the area of the Southern Cross/ Milky Way with a mythical Ñandú (Rhea americana). Such an interpretation has allowed us to raise the possibility that we are being faced with the integration of knowledge of the sky in the form of the social construction of inhabited space and the configuration of the landscape.