Throughout history, armies, kings, merchants and pilgrims have crossed the San Adrian Tunnel. As a crossing point, its origins go back to antiquity, to Roman times. At that time, the road linked Astorga with Bordeaux, still guiding the visitor’s steps on both sides of the opening. Since the 11th century the tunnel was mostly used as the natural road of communication between the region of Llanada Alavesa and the Guipuzcoan valley of the River Oria; a transit point between Castile and the rest of Europe.
In 1290, Pope Nicolás IV awarded privileges to pilgrims, passers-by and beggars who on the day of his feast, would visit the hermitage of San Adrián, inside the tunnel. In its heyday the place was endowed with facilities, a tavern, stables and a permanent guard among others. The hermitage even had a mayor’s office, and one of his mayors even boasted of being one of the most important people of all of Europe, of the most distinguished rich men and nobles of the continent.
Because of the narrow exit of the tunnel the majority of visitors had to bend over and uncover their head. Moreover, the passage was not free of charge as evidenced by the remains of the old medieval customs, which, on the Guipuzcoa side, are nowadays the entrance to the pass.
The tunnel is also one of the key points of the initial point of the inland Way to Santiago. Since the Alava pilgrimage route came up as an alternative to the coastal route (which sometimes turned out to be too dangerous because of the partisan fights and banditry, especially in Guipúzcoa and Vizcaya between 14th and 15th centuries), the pilgrims took advantage of the ancient Roman road to travel from the Basque coast towards the city of Vitoria. Due to the intense darkness inside the tunnel, it soon became known as the “Mouth of Hell”.
In 1502 princes Phillip I called the Handsome or the Fair and Joanna known as the Mad, passed through the tunnel during their trip from Flanders to Castile. Both stopped in the hermitage of the tunnel to act as godparents of Felipe de Lazcano (named after the prince), son of the famous sailor and military Juan de Lazcano, escort of Phillip I, born in the area.
The improvements made communication routes during the 18th century were subtracting traffic to San Andrián Tunnel, which would be abandoned in 1851, when the highway crossing the massif through the port of Etxegarate was inaugurated. Nowadays it is a natural first-rate tourist resource.