Calatayud is a municipality in the Province of Zaragoza, within Aragón, Spain, lying on the river Jalón, in the midst of the Sistema Ibérico mountain range. It is the second-largest town in the province after the capital, Zaragoza, and the largest town in Aragón other than the three provincial capitals. It is the seat of the comarca of Calatayud. The city has the title Muy noble, leal, siempre augusta y fidelísima ciudad de Calatayud.