Built at the initiative of Bishop Diego Gelmírez between century 12 and century 13, is considered the best work of Romanesque peninsular. It was the archbishop's residence for many centuries.

Its Baroque façade, rebuilt in the eighteenth century the original (Roman), together with the cathedral, it gives an idea of its interior and well worked with numerous chimneys, narrow passageways and stairs leading to rooms among which the Refectory.