If we want to know Amposta, one of the essential points of visit is the Castle, an ancient fortress of the 10th century defended by Arab and medieval walls. It was erected on the banks of the Ebro river, on an Iberian settlement. In the 12th century it was conquered by Count Ramon Berenguer IV and became the seat of the order of St. John of Jerusalem of the Kingdom of Catalonia and Aragon. After successive wars, it was abandoned and became a quarry from where the blocks were taken to supply other buildings of the village. Later a rice mill was installed was installed in it. A series of information panels allow you to tour the enclosure that currently houses the base of the tower of Sant Joan, the moat and a few slender stone arches located next to the river. In addition, one can also visit some Iberian silos and remains of the mill. The complex has been was by the City of Amposta and currently concentrates much of the cultural activity of the city, like the Art School, the Sebastià Juan Arbó Library, or the Institute of Regional Studies, among others.