The paper focuses on a description of the techniques, both photogrammetric and geodetic, used for the data acquisition and processing concerning the project “Development of Geographic Information Systems at the Acropolis of Athens”. Aiming at the development of a Geographic Information System which will incorporate large-scale orthophotomosaics for the walls, an orthophotomosaic of the top view of the site, as well as a dense textured 3D surface model of the walls along with the rock, the project is divided into three basic tasks: the geodetic, involving field measurements for the generation of a polygonometric network and terrestrial laser scanning of the walls along with the Erechtheion monument, the photogrammetric one involving image acquisition, orientation, DSM generation and orthorectification, and finally the development of the GIS. This contribution underlines particularly the methodologies applied highlighting simultaneously the potential of combining photogrammetry and state-of-the-art geodetic techniques (laser scanning) for an accurate 3D modeling of cultural heritage sites.