The Nasca Lines around Palpa are currently investigated by archaeologists and geodesists from Switzerland, Germany, and Peru. A photogrammetric analysis of high resolution aerial images allowed the accurate 3D recording of more than 1500 geoglyphs, most of which have also been thoroughly described in the field. A digital 3D model of the area of investigation is the first important result of this effort. However, the vectors recorded during the mapping process that mark the preserved outlines of the geoglyphs do not coincide with the geoglyphs themselves, which contain also an interior surface. Furthermore, they show certain traits important for an archaeological analysis, some of which (geometric attributes like location, size, and orientation) can be derived from the processed vector data, while others (contextual attributes like stratigraphic relations and associated objects) have been recorded during fieldwork. An important prerequisite for the intended GIS-based analysis of our data is to define meaningful archaeological objects (i. e., the geoglyphs) and assign them different kinds of attributes like those mentioned above. In this paper we describe the original data, the process of object definition, and our data model and discuss some preliminary results.