The Sub-Angstrom microscope ARM200F installed at IMM-CNR is a new class of electron microscopes denominated Cs-corrected equipped with a special lens which makes possible the correction of spherical aberration, which is known to be the main obstacle to the resolution, allowing the achievement of a sub-Angstrom resolution. The spherical aberration is a feature of all the round lenses that cause distortion of the image. Galileo (1565-1642) was the first scientist to deal with this problem in the field of optics, and at that time it was unclear why a lens was better than another. Subsequently was Ernest Abbe in 1860 to understand the problem and provide the basis for the engineering of optical lenses. About a century later (1930) Ernst Ruska developed the first electronic microscope (for which he was awarded the Nobel Prize for physics in 1986) and in 1936 Otto Scherzer, describing the analogy of spherical aberration in electron microscopy, he was the first to theorize that the perfect lens is not feasible and that only a correction of spherical aberration can solve the problem. It took seventy-five years to see the introduction of correctors in transmission electron microscopes and today a new generation of tools will enable studies in solid state physics and materials science and can achieve and exceed the resolution on the atomic scale. These new possibilities meet the growing demand of nanoscience and nanotechnology for the characterization of materials and devices nanosintetizzati, resulting in the ability to discover those properties known only theoretically.