The conquest of Sigüenza by Bernardo de Agén Historical milestone · Sigüenza, Serranía de Guadalajara, Guadalajara Image of Sigüenza, not of the place itself. On 22 January 1124 the Aquitanian bishop Bernardo de Agén took the city from the Muslims and remained at its head as episcopal lord. Shortly afterwards he began the building of the cathedral, which made Sigüenza the ecclesiastical and administrative head of the sierra. 1124 Photo: Cruccone (CC BY-SA 3.0 es) What to see and do in Sigüenza