The investigations that are made on a building for conservation purposes need an important work that is transcribed in a variety of numerical and printed data: surveying data and scientific imagery, damage mapping, photographic collections, historical archives, physical and chemical data etc. Given the difficulty to collect, compare, analyse and validate data prior to restoration, the approach we present aims to mobilize various disciplines (architecture, conservation, mechanics, and computer sciences) to define a novel information processing chain including metric surveys, analysis of surfaces, geometric models of structures, heterogeneous documentary sources management, temporal data, etc. By the way of MONUMENTUM project which is an on-going research project (2013-2017) funded by ANR (French National Agency for Research), we are designing and developing an open and expandible web platform for the capitalisation and the management of knowledge needed for the understanding and analysis of degradation phenomena affecting historic buildings. This objective requires the definition of a common and continuous process that establish a technological and conceptual interconnection between the stages of 3D digitization, semantic annotation and structuring of the geometric model (including multi-layers analysis of surfaces), characterisation of the state of the building and management of restoration actions. Based on three case studies that present conservation issues on stones (Castle of Chambord and Caromb’s church in France) and wall paintings (Notre-Dames des Fontaines’ chapel in France), it concerns the image-based- modelling of architectural heritage, the development of a 3D information system for the management of conservation data and also a numerical modelling tool (FEM-DEM) for the physical and structural analysis.