The landscapes of the Asiago Plateau (NE Italy) underwent profound transformations during World War I due to the construction of extensive fortifications and defense systems. These changes were meticulously documented by military tactical maps throughout the conflict. Studying these WWI military tactical maps, also in a GIS environment, appears to be of paramount importance for studying war landscapes, allowing for a better analysis of their characteristics and their evolution over time. However, methodologies for mapping operations, especially for a unique classification of the different topographical features, seem to be not fully experimented within a GIS environment, yet. The main objective of this research is the construction of a Historical GIS database of immobile or semi-mobile military elements (such as trenches, field works, and artillery emplacements) found in historical military maps of World War I in the Sette Comuni di Asiago area. Austro-Hungarian, British, and Italian maps of the area have been digitalized using a series of guidelines and a common database of symbols, which has been built to aggregate information coming from different cartographical sources. Problems regarding the inconsistency of symbols among the different maps, the loss of information due to generalization of maps, and the topographical accuracy during digitalization have been addressed, to create a detailed and accurate database of military elements. This database could be used to analyze unexplored themes in the study of XX century war geohistorical dynamics, supporting and enhancing military history and geographical investigations in the context of World War I.