Immuno-electron microscopy studies on the morphology of the Escherichia coli ribosome and the topography of its functional centers are summarized. A three-dimensional model of the ribosome with indications of the mRNA-binding site, the peptidyl-transferase center, the EF-Tu and EF-G-binding sites and the tRNA-binding sites in given. Thus, the mutual arrangement of the centers corresponding to the main functional activities of the ribosome during the process of translation is presented.