Researchers from the University of Cádiz in Spain focused on settlements in the areas surrounding Arcos de la Frontera, Bornos, Villamartin and Puerto Serrano which would have all been interconnected by the Guadalete River, leading them to believe that they were part of a hidden empire.The team said they used geo radar - a tool that sends radar pulses underground to detect any hidden objects.They used geo radar technology to locate the wall structures from ancient residences that weren't visible from the surface...The researchers discovered that the villa had walls separating the residential and work areas while they were trying...