: Two main problems arise in modelling data warehouse structures. The first consists in establishing an adequate representation of dimensions in order to facilitate and to control the analysis operations. The second relates to the modelling of various types of architecture. Research work dedicated to the first problem has been conducted, and adequate solutions have been proposed. The second problem has not received so much attention. However, there is a need to apprehend complex structures interconnecting dimensions and facts in various ways. In this paper, we propose a model through which dimensions at different levels can be shared between different facts and various relationships between these facts can be described. Using this model, we then define the notion of well-formed warehouse structures.