In Galicia, Asturias, Cantabria, Basque Country, province of Ávila and Northern Portugal a castro is a fortified pre-Roman Iron Age village, usually located on a hill or some naturally easy defendable place.[21] The larger hillforts are also called citanias, cividades or cidás (English: cities). They were located on hilltops, which allowed tactical control over the surrounding countryside and provided natural defences. They usually had access to a spring or small creek to provide water; some even had large reservoirs to use during sieges.