Jalón river plain in Alagón Nature · Alagón, Ribera Alta del Ebro, Zaragoza Image of Alagón, not of the place itself. In the fertile valley where the Jalón flows into the Ebro sits Alagón, which occupies the site of the Iberian city of Alaun, later called Allabone in Roman times; taken by Alfonso I in 1119, it retains from that frontier stronghold the tower-minaret of its former mosque, reused as a Christian bell tower. Photo: Zarateman (Public domain) What to see and do in Alagón