Mediterranean societies were characterised by multiple and shifting frontiers during the Middle Ages, a formative period for modern Europe. These frontiers were created by periods of conflict between opposing societies defined, above all, by religious differences - between Christians, Muslims and Jews, but also between different groups of Christians. All these frontiers absorbed existing communities and supplemented them with migrants. They were governed by authorities from imposing castles, whose remit was to ensure security and promote the ideology of the conquerors. As the most striking material legacy of the former frontiers, today these castles are the focus of regional and national tourism, tied into narratives of cultural struggles. However, they remain disconnected from their associated territories, both in the academic and public domains. As frontiers, these territories encompassed multicultural communities and articulated tensions between the conquering authorities and conquered populations. This project will address this disconnection between frontier castles and their cultural landscapes, with two aims. Firstly, to broaden regional and international interest in the full spectrum of medieval heritage in South West Europe, building on existing interest in iconic monuments. Secondly, to develop public awareness of past multiculturalism as an essential context for the current debate on migration and multiculturalism, especially since traditional historical narratives are regularly used to validate political and social agendas. This will entail a comparative investigation of three different frontier regions in Spain and Pyrenean France. The key questions we will ask are how did conquering authorities deal with the creation of multicultural societies in these frontiers, how did they relate to central authorities and how did conquered communities respond to the imposition of new political and social norms? Drawing on a range of archaeological, environmental and historical data, we will investigate changes in settlements, religious, commercial and political centres alongside environmental changes, assessing whether territorial reorganisation resulted in intensified resource exploitation, or to what extent earlier trends continued and can be linked to established practices and worldviews. We will then consider how much freedom there was to move across these frontiers, traditionally linked to the widespread practice of transhumance. Finally, we will bring all this information together and produce a comparative map of what we will define as cultural resilience - the ability of conquered communities to adapt to the imposition of a new regime. Environmental exploitation is an increasingly used index of this resilience. We will then develop a visual and digital infrastructure to enable visitors to engage with the cultural landscapes associated with the iconic monuments of frontier authorities.