This paper attempts to analyse the land transport in Roman times in mountainous areas, taking into account the most feasible location for the road infrastructures as well as the conditions for different means of transport. With the use of different GIS applications such as LCP (Low Cost Paths) and Network analysis, the study aims to recognise the time, effort and cost that was involved in crossing important mountainous barriers such as the Pyrenees and the Alps. In spite of the lack of an economic return, the Roman Empire invested a lot of resources in building complex infrastructures up in mountainous regions. This paper addresses the reasons behind such an economic effort.