La Guardia de Jaén or Guardia de Jaén, La, and the old Mentesa Bastia at Iberic and Roman era, is a small city located in the province of Jaén at western end of Sierra Mágina, on the Cerro de San Marcos, near the promontory of Cerro de San Cristóbal, from where it dominates the valley of the river Guadalbullón. With a population of 4061 inhabitants-according to January 2009 census-, is situated 635 m over sea level, with an area of 38.43 km2.