Central Portugal, delimited by the Douro river to the north and the Mondego to the south, is the second densest region of megalithic monuments in the country. The Neolithic archaeological record indicates seasonal transhumance between higher pastures in the summer and lower grounds in the winter. The monuments are found in lower ground and it has been suggested that they were built during the winter occupation of their surroundings. The astronomical orientation of their entrances lends further support to this hypothesis. A recent survey of the orientation of the chambers and corridors of these dolmens, conducted by the author, found good agreement with prior surveys, but also demonstrated that other interpretations are possible. This paper presents an update on the survey, including extra sites surveyed in the spring of 2011, as well as the GIS confirmation of all horizon altitudes that couldn’t be empirically measured. The megalithic nucleus of Carregal do Sal, on the Mondego valley, is then looked at in more detail. It is found that there is a preference for the orientation of dolmens towards Star Mountain Range in-line with the topographic arguments of landscape archaeology. In addition, it was found that the topography also marks the rise of particular red stars, Betelgeuse and Aldebaran, during the period of megalithic building, at the onset of spring marking the transition from low ground to the high pastures. This hypothesis finds further support from toponymic folktales that explain the origin of the name of the mountain range.