This article Summarizes our recent effort to fabricate electrochemically metallic nanowires and electrodes separated with molecular scale nanogaps. The nanowires were fabricated by etching a small portion of a micron-scale metallic wire supported on a solid substrate. The etching was controlled by continuously monitoring the conductance of the wire. When the thinnest portion of the wire reached the atomic scale, the conductance decreased in a stepwise fashion. By further etching away the last few atoms, a molecular-scale gap between two electrodes was created and the ballistic electron transport through the nanowire was replaced with quantum tunneling. By depositing atoms back, the above processes could be reversed, allowing us to achieve a desired nanowire or gap. The nanowires may be used for chemical sensor applications and the nanogaps may be used to wire small molecules to the outside world for molecular electronics applications.