Cultural landscapes often pose problems for planning and management because of insufficient information regarding visitor movements, interests and infrastructure burden. Traditionally visitor surveys have helped to fill this gap, albeit limited to their incomplete and occasional nature. This paper presents a methodology for using cellular antenna metadata for understanding tourism flows. This information is collected systematically by the mobile phone network but only recently has its big data potential begun to be exploited for understanding socio-economic phenomena. The present case study of the Roman gold mine of Las Médulas (León, Spain) provides a model for tourism impact analysis using anonymized data from cell phone towers.