Martos is a city and municipality of Spain belonging to the province of Jaén in the autonomous community of Andalusia. With a population of oveā¦Martos is a city and municipality of Spain belonging to the province of Jaén in the autonomous community of Andalusia. With a population of over 24,000 people, Martos is the fifth largest municipality in the province and the second in Jaén metropolitan area. Housing lies at the foot of the 1,003-metre Rock of Martos, on the western side of the Sierra Sur de Jaén, a subrange of the Baetic System, in the south of the Iberian Peninsula.