In this range of hills there exist two megaliths, two dolmens to be precise, known as the Arobigaña dolmen and the Atxuko Aldai dolmen.

In contrast to the sites in eastern Gipuzkoa, cromlechs are not known at the Aratz-Alsasua site.
The megaliths of the Aratz-Alsasua mountain range are located in the Partzuergo Orokorra of Gipuzkoa and Araba (Urbia), and the Partzuergo of Altzania.

Aratz-Alsasua