The frontier of the March at Montmell Historical milestone · el Montmell, Baix Penedès, Tarragona Image of el Montmell, not of the place itself. The sierra was during the tenth century a frontier line between the Catalan counties and the Andalusi territories. Its castle, documented in those years, controlled the passes towards the plain and organised the later repopulation of the Penedès. siglo X Photo: Angela Llop (CC BY-SA 2.0) What to see and do in el Montmell