This natural park boasts the highest summits in the whole Basque Country: Aitxuri, 1,551 metres high and Mount Aizkorri, standing 1,528 tall. The rock offers some exceptional views to the south of Gipuzkoa and the Alava plains. Actually, Gipuzkoa is so small that from the top of a great mountain like Aizkorri, you can see all the others, throughout the entire province, like looking at a real scale map. The source of the Oria, Urola and Deba rivers lie among these limestone ridges that have formed both a defensive wall keeping this land safe and a formidable obstacle that man has had to cross since time immemorial: St Adrian’s Pass, a tunnel carved out of the rock, also home to a hermitage, a fundamental milestone along the St James’ Way and connections between the Castilian Plain and Europe. The Zegama and Arantzazu Parketxes will give you all the information you need.