Nanoparticle crystals or superlattices (SLs) are three dimensional arrangements of nanoparticles in the micrometre regime. In SLs, the particles are periodically arranged in a coherent long range order and hence they show collective properties. Various spectroscopic, scattering and imaging techniques have been used to understand the structure of self-assembled SLs. Extensive interest in particle SLs is due to the collective properties of the building blocks, which help us to understand the evolution in properties of organized structures. Controlling the assembly of such organized solids may open up new opportunities for fundamental studies as well as for engineering advanced materials with useful attributes. This review presents our efforts in creating SLs of noble metal nanoparticles and studies performed with those materials. © the Owner Societies 2011.