Submerged Memories: A Typological Analysis of Medieval Crypts in the Mediterranean Region

The debate on underground architectures has become particularly pronounced in the last twenty years. Specifically, following past stone excavation activities, some cities now face a high risk of ground subsidence (sinkholes) and, consequently, building collapse. Commonly known as "artificial cavities," these are empty spaces constructed underground, sometimes inhabited and adapted by humans throughout history, according to various needs and uses. Significantly and widely present in the Mediterranean basin, collectively they constitute a historical landscape in reverse, a part of collective memory hidden and forgotten beneath the city's surface. Indeed, this phenomenon has mainly been addressed by the discipline of geology, which is why in some countries, such as Italy, censuses on sinkholes and urban hypogea have been initiated. Furthermore, the recent tourist success of some recovered and enhanced underground sites, such as in Naples, has brought to light the material and immaterial values of the underground heritage, promoting new interests and research. Starting from this premise, this research emphasizes the need to further investigate and delve into the topic of underground architectures, particularly in their interrelation, both material and immaterial, with the "emerged" city. It is essential to begin with an in-depth typological analysis to discern the identity of these complex spaces and recognize potential transformations, chronologies, and relationships. Employing a multi-scalar approach and following an investigation into the typological variations of cavity architecture, the article presents a more detailed typological analysis of medieval crypts excavated in the Mediterranean region. More specifically, this article will focus on the case study of Sardinia. This investigation will subsequently allow for the definition of a set of indications through which to study and understand these specific assets. Forming the basis of a new interdisciplinary methodology coordinated by the discipline of Restoration, this approach aims to facilitate the knowledge, preservation, and valorisation of underground archaeological and architectural heritage.