During the presentation I will talk about my background using different biological samples and 3D structural methods at different levels of resolution. Briefly, the talk will be organized in 3D electron transmission microscopy methods to resolve viral structures (influenza A virus RNP and tail complex of T7 bacteriophage) and correlative approaches, between conventional fluorescence microscopy and transmission soft X-ray microscopy, to tackle the accumulation of superparamagnetic iron oxide nanoparticles in in vitro cultured cells. I will conclude with a summary of my future projects.