Of the many existent dolmens in the District, only the Dolmen "Foz do Rio Frio", in Ortiga, is standing.
There was several megalític monuments, of what most are already destroyed. Oppositely to the monuments that are recognized in west, in the valley of the Zêzere, that are grouped together in sets of two to five monuments, forming cemeteries, the Mação monuments appear isolated, generally in elevated positions and "looking" at the fertile valleys.
The digging of the Dolmen "Foz do Rio Frio" revealed the construction of a monument of camera and short corridor paved and recovered by a complex mamoa, with clear affinities with the phases calcolíticas of the monuments of the valley of the Zêzere. However, there are products in quartzito, of "paleolithic" appearance, and some sub-circular axes, which suggest the most ancient presence of a phase.
The last use of the Dolmen "Foz do Rio Frio" is dated around 4.300 years ago. This grave marks a moment of turning, in which the individual status surfaces on the community, which on his side it begins to invest more in constructions for the living creatures (and not only for the dead men), when a territory of fighting communities takes place, in growing tension for the possession of the lands and his products.