Nowadays, there are an emergence of spatial or geographic data stored in several and heterogeneous databases, mostly in Geographic Information Systems (GIS). The diversity of GIS and the increasing accumulation of non-spatial (simple attributes) and spatial (geometric shapes) data make it difficult to apply conventional OLAP and data mining tools. Thus, the need to build a spatial data warehouse over heterogeneous GIS is becoming necessary in many fields. Our architecture is a central type architecture based on GML (for spatial data representation) and more generally on XML (for all data). In this paper we will focus on the study of data integration into a data warehouse, and data representation. We will show how the specificities of our architecture contribute to manage spatial and non-spatial data.