How our ability to now see the invisible is central to research in biology – from infectious disease to cancer and Alzheimers. The development of the electron microscope in the middle of the last century revolutionised biology and our understanding of cells and tissues. Developments have continued and in this century computation methods have enabled 3D imaging of complete cells. I will show, using images of diverse cells and life forms, how our ability to now see the invisible is central to research in biology – from infectious disease to cancer and Alzheimers.