A unique civil Romanesque building, probably dating from the 12^th century. It may have been the market hall which in medieval documents is referred to as the “San Martín portico”, which belonged to the monastery of Irache and housed a number of shops. At that time, the building comprised only the portico with four arches and an upper floor with palatial four-arched windows. Later (17^th century), the building was extended, this time using brick, in the Navarro-Aragonese Baroque style.

In the 15^th century it became the palace of the Marquises of Cortes —members of the royal family who held the position of Marshals of Navarre—, who later in the 18^th century were to be granted the title of Dukes of Granada de Ega.

From 1868 until at least 1941 it was used as a prison. Following the military coup of 1936, a great many people from the city were incarcerated here, among them the mayor, Fortunato Aguirre, who was taken from here together with others to be shot.

From an artistic perspective, of particular interest are the columns that sit at either side of the façade: on the left, we have the capital bearing a representation of the confrontation between Roland and Ferragut, a reminder of the great exploit at the battle of Roncevaux and closely related to the Way to Santiago, in which the Christian knight pierces with his lance the giant’s only weak point, his navel; on the right, the capital bearing symbolic representations of some of the deadly sins, such as pride (an ass playing the harp), greed (two convicted criminals with bags around their necks), and lust (a woman with snakes hanging from her breasts).

Despite its popular name as palace “of the Kings of Navarre”, no documented proof has ever been found of Navarrese monarchs having stayed in this building.