Our work involving the application of solid state chemistry in the context of cultural heritage has followed two main routes: archaeometric (including provenance), in which we have studied degradation products and mineralogical composition of materials, and restorative (including preventive, diagnostic and conservation studies). Powder X-Ray diffraction is central to our work in this area, allowing us to: determine mineralogical composition, observe the solid state behaviour of pigments used for decoration, study degradation products of materials having cultural significance (such as paintings, ceramics, ancient manuscripts, stone or metal objects). We have used crystal engineering techniques to alter the properties of pigments typically used in paintings and stone ornaments.