The palace was originally an austere building that was strategically positioned at the end of a terrace of houses on the boundary of the old medieval town. It therefore had three facades: One looking out onto Barrenkalea Street, one onto the square Plaza San Martin, and the one on the back giving onto Domingo Irala. This last one still retains the typical elements of the late 15th century (Gothic features, stone corbels, and pointed window).

From 1725 onward, the house was thoroughly refurbished, gaining an extra floor, with the building of the other two facades with numerous large French windows looking out onto the main Barrenkalea street and the town’s main square, the site of gatherings and festivities, with the edifice thereby acquiring its current palatial status.