DIACHRONIC RECONSTRUCTION OF LOST CULTURAL HERITAGE SITES. STUDY CASE OF THE MEDIEVAL WALL OF AVILA (SPAIN)

The integration of the fourth dimension into the geospatial data allows to generate a diachronic model of Cultural Heritage (CH) assets, namely, a set of 3D models to represent it in various historical phases. This kind of reconstruction pursues a better understanding of the CH site/scenario, enriching the historical hypotheses as well as contributing to the conservation and decisionmaking process. Although the new geotechnologies have reduced the amount of fieldwork, the generation of 4D model implies the interpretation of heterogeneous historical information sources and their integration. However, this situation could reach a critical point when the study elements are no longer present. Their reconstruction will allow the digital preservation and maintenance of our culture. The main challenge is to harmonize the different historical and archaeological data sources available in relation with the current remains, to recover the lost CH assets with a high degree of reliability. This manuscript aims to examine the study case of a diachronic reconstruction by means of the use of the geotechnology Mobile Laser System (MLS) and reverse engineering techniques for a lost urban CH element, the citadel or <i>Alcázar</i> Gate of Ávila. Within this aim, the derived product is evaluated in terms of the achieved accuracy to assess its suitability on the basis of constructive interpretations required to integrate the historical sources in relation to current remains and the surrounding