Plasmonic nanostructures are very efficient at generation of heat under optical excitation.  Under certain conditions, optically driven gold nanoparticles (NPs) can significantly increase temperature of a medium or even melt a surrounding matrix. The heating and melting processes occur under light illumination and involve the plasmon resonance. Melting and heating of the matrix become possible if a nanoparticle size is large enough. Significant enhancement of the heating effect happens in assemblies of NPs owing to the heat accumulation effect and the plasmonic field amplification. As one of the current applications, the collective photo-thermal effect in NP assemblies (aggregates) is  employed for heating and actuation of biological systems and media.  If a nanostructure is of low symmetry, it may be chiral and exhibit circular dichroism at the plasmonic frequency. In that respect, chiral nanoparticle assemblies (helices and pyramids) look especially interesting.