This paper on perceptions of the Pontine Region in Central Italy starts out with a discussion of a map by the Renaissance artist and engineer Leonardo da Vinci which he made of the Pontine marshes in the early 16th century A.D. Since this map is the earliest rendering known of this former wetland, it is an important document for the reconstruction of the wet areas of the Pontine Region, a landscape unit that falls within the wider survey area of the Pontine Region Project.1 The example shows how deconstruction of historical documents, whether texts or maps, is a prerequisite for an understanding of how landscapes were differently perceived over time. After all we perceive what we want to see. A valid interpretation of Da Vincis's map for archaeological purposes requires, however, insight into both the context of the map and the way in which Leonardo da Vinci handled landscapes in his work. I discuss the map to demonstrate how archaeologists using historical and ethnographical documents run the risk of dealing with ‘outsider’ information whilst thinking they are dealing with sources that take them right inside the landscape, i.e. into the landscape of its past inhabitants. To avoid the pitfall of perceiving what one wants to see, the archaeologist is recommended to obtain insight into the various historical perceptions of his study area. I cite some instances from my work that show how it is possible to extract inside information from ‘outsider’ maps and texts concerning the Pontine Region. It is argued that such inside information is needed to complement Mediterranean survey methodology if the discipline is to develop landscape perception models of Mediterranean regions in antiquity that are not based on a priori notions. The delineation of preference surfaces in the landscape such as forwarded by the archaeological record, is proposed as a starting point for reconstructions of past collective perceptions.