Anta de Adrenunes

4500-3000 BC: The Anta de Adrenunes is a Neolithic dolmen in Sintra, Portugal, perched at 426m on a hill within the Sintra-Cascais Natural Park[1][2]. The monument features a 5m-high gallery formed by granite orthostats supporting horizontal capstone monoliths[1]. While believed to have functioned as a collective necropolis, no burial artifacts or human remains have been discovered to confirm its purpose[1]. A modern geodesic marker has been inserted into one of the upper stones[1]. The structure represents a rare example of megalithic architecture in the Sintra region.