The Castro of Monte Valinhas is an Iron Age hillfort settlement in the parish of Santa Eulália, a few kilometres from Arouca town. The site sits on a prominent ridge with wide views over the surrounding mountains and valleys and shows evidence of occupation from the late prehistoric period through to early medieval times.
The castro is less developed as a visitor site than its archaeological significance might suggest — there are no formal facilities, and the ruins require some imagination to read. But the setting is striking and the walk up gives a sense of the defensive logic of these hilltop settlements. It is worth combining with a drive through the schist villages of the geopark territory rather than as a standalone destination.