San Vicente Castle is located on the top of a hill overlooking the River Ebro. When it was built it was the largest fortress in Navarra built close to this river, comprising part of the Laguardia and Labastida lines of defence. It was built after 1170 or 1172 under supervision by Ferrant Moro, commissioned by Sancho el Sabio of Navarra, who in 1172 gave it the title of township, converting it into the property of the Crown. The solid structure of its walls and its advantageous position dominating the Ebro, must have made it impregnable.