The preservation of built heritage is one of the great challenges of our society, as they play a key role in the construction of the collective memory. ICOMOS Charter (2003) sets out that a full understanding of the structural and material characteristics is required in conservation practice. This means studying the structure's current state, but also its original state, historical data and building techniques. The development of massive data capture techniques (MDC) in recent years, such as the Terrestrial Laser Scanner (TLS), together with current structural analysis procedures makes it possible to understand masonry historical constructions as never before. The investigation presented is focused on a case study, the main body of Tortosa Gothic Cathedral. A combination of geometrical and structural analysis procedures are used to assess the structure, considering the partially-known construction stages. A simple, non-invasive methodology for the assessment of masonry vaults from point clouds is used to obtain relevant data about formal anomalies. In addition, limit analysis by means of thrust lines allows to identify possible stability issues during construction. The results obtained allows to enhance the knowledge about building's history, which is essential for its preservation.