Anta de Adrenunes is a prehistoric dolmen or megalithic monument located in Colares in Portugal. It is one of the largest and most well-preserved dolmens in the region, dating back to the Neolithic period, around 5,000 years ago.

The dolmen consists of several large stones, including a large capstone, which rests on top of several upright stones forming a chamber. The entrance to the chamber faces east and is marked by two massive portal stones. The dolmen is surrounded by a circular mound of earth, which was likely used to mark the site and to provide support for the stones.

The purpose of dolmens like Anta de Adrenunes is not fully understood, but they are thought to have served as burial chambers or ritual sites for prehistoric communities. The stones used to construct the dolmen would have been quarried and transported over long distances, indicating a high level of organization and social cooperation within these communities.