Fuerte de San Cristóbal y la fuga de 1938 Historical milestone · Ansoáin/Antsoain, Comarca de Pamplona, Navarra Image of Ansoáin/Antsoain, not of the place itself. The Fuerte de Alfonso XII, known as the Fuerte de San Cristóbal, was built between 1878 and 1919 on Mount Ezkaba, within the municipal boundaries of Ansoáin, and from 1929 functioned as a military and later civilian prison. During the Civil War it became a political prison; on 22 May 1938 the largest prison escape in contemporary Europe took place, when nearly 800 prisoners broke out of its facilities. Of these, 206 died during the pursuit or were executed afterward, only three reached the French border, and fourteen of those recaptured were shot as ringleaders. It was declared a Bien de Interés Cultural (Spain's highest level of heritage protection) on 16 November 2001 (code RI-51-0010464). 22 de mayo de 1938 Photo: Zarateman (CC BY-SA 3.0) What to see and do in Ansoáin/Antsoain