Anta da Casa dos Mouros/ Foz do Rio Frio

Anta/Dolmen - Neolithic e Chalcolithic (Copper Age) (854)
The Anta da Casa dos Mouros or Anta da Foz do Rio Frio is located on an isolated position, atop a hill, at the conjuction of the Rio Frio and Rio Tejo, dominating a wide territoy. This megalithic monument, facing east, presents a polygonal chamber (measuring 2.90m in diameter), composed by eleven granite orthostates and slab pavement, and a 3.50m long by 1.10m corridor, formed by five orthostates on the right and left sides. Traces of the mamoa can be found on the outside, formed by a lithic ring, compressed with clay extracted from the Rio Frio banks. The artefact collection was mostly recovered from the mamoa and corridor areas, with only traces being identified inside the chamber. The collection is composed of lithic-flaked artefacts (trapezes, triangles, crescents, a silex halberd, silex knives, convex arrowheads, rock-crystal quartz blades and scraper), polished stone (axes) and shaped stone (querns) artefacts, two shale plaques and a sandstone plaque, fragments of undecorated ceramic vessels (two carinated vessels) and a copper dagger. The architectonic characteristics of this dolmen, combined with the recovered artefacts, allow to identify two chronologically distinct occupation periods. The first can be framed in the late 5th millennium and first half of the 4th millennium BC (Mid and Late Neolithic), which would match the construction and most intense utilisation of this dolmen. The second moment happens when this structure was reused during the late 3rd millennium (Late Chalcolithic), with two funerary depositions in the corridor having votive artefacts which included two undecorated carinated ceramic vessels, a copper dagger, a stone wrist-guard bracer and an arrowhead, in line with the Bell Beaker traditions. The chronological diversity of ritual and funerary occupations of Anta da Casa dos Mouros / Foz do Rio Frio stands as evidence of this monument's complexity and symbolic longevity.


Free access. For a guided tour should contact the Museu de Arte Pré-Histórica de Mação - Instituto Terra e Memória. The monument is integrated in the circuit "Lithos - Archaeological Circuit of the Tagus Valley".

Visit conditions

Free entrance




How to get there? Best practices

Best practices

Good practices when visiting archaeological sites

To visit an archaeological site is to connect with our origins, to understand our path and evolution as a species integrated in the environment, and to respect and safeguard our heritage so that future generations can also visit and enjoy it.

Walking the paths and enjoying the structures and archaeological pieces that survived over time, fosters the understanding of what is different, but also of what is common among different populations: basically, what identifies us as Homo Sapiens.

More than just vestiges and ruins of the past, archaeological sites showcase our capacity for creative thought, adaptation, interconnection, comprehension and resilience. Without these traits we would not have been successful as cultural beings participating in an ongoing evolutionary process. These sites also allow to consider choices made in the past thus contributing for decisions in the present to be made with greater awareness and knowledge.

Archaeological sites are unique and irreplaceable. These sites are fragile resources vulnerable to changes driven by human development. The information they keep, if destroyed, can never be recovered again.

As such, the Directorate-General for Cultural Heritage (DGPC) invites all visitors to enjoy the beauty and authenticity of these sites, while helping to preserve them for future generations by adopting the following set of good practices:

  • Respect all signs; 
  • Do not try to access fenced areas; 
  • Do not climb, sit or walk on archaeological structures and remains; 
  • Respect areas where archaeological excavations are being carried out, not disturbing them; 
  • Do not collect materials or sediments;
  • Do not write or make graffiti on archaeological structures; 
  • Put the garbage in appropriate containers. If none exist, take the garbage with you until you find a suitable container; 
  • Leave the archaeological site as you found it; 
  • Do not drive bicycles or motor vehicles over archaeological sites; 
  • Respect and protect the plants and animals that live in the areas surrounding archaeological sites;
  • Report signs of vandalism or destruction to DGPC or Regional Directorates of Culture (DRC);
  • Share the visiting experience and the archaeological sites, as a way of raising awareness to their preservation and making them better known;
  • Do not buy archaeological materials and report to public security authorities, DGPC or DRC, if you suspect that archaeological materials may be for sale.

Further information:

AIA / ATTA (2013) – Guide to best practices for archaeological tourism. 

Raposo, J. (2016) – Código de conduta para uma visita responsável a sítios arqueológicos. In Sítios arqueológicos portugueses revisitados: 500 arqueossítios ou conjuntos em condições de fruição pública responsável. Al-madan, 2ª série, p. 20 – 77. 

DGPC contacts

Phone: +351213614200 | Email:


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