One-dimensional (1D) metallic structures, self-assembled on semiconductor surfaces (surface superstructures) are discussed, showing the characteristic atomic arrangements, band dispersions, Fermi surfaces, phase transitions, and electronic transport properties. Experimental techniques for directly probing the structures and properties, such as four-tip scanning tunneling microscopy, the monolithic microscopic four-point probe method, and angle-resolved photoemission spectroscopy, are also introduced. Owing to the good controllability of the surface structures and the direct accessibility by the experimental techniques, the surface-1D systems are now a new platform for nanometer-scale 1D physics.