Since the focus when modeling solids and more generally in condensed matter physics (CMP) is on energies, physical sizes, and time scales that are not extremely big or extremely small, but somewhere we loosely call the “middle”, it can be argued that this characteristic of CMP allows it to have many links to other branches of physics and more generally other areas of science and engineering since many of them also focus on similar size scales. In addition, the domain of CMP includes both applied and fundamental components. Although I will focus mainly on the latter with emphasis on “modeling solids” which gave rise to many intellectual and conceptual contributions to basic science, I will mention some applied aspects. I plan to describe some research involving the electronic structure of materials, semiconductors, superconductors, and nanoscience. I’ll begin with a discussion of the development of these areas over the past hundred years, and then I’ll discuss some current achievements and discoveries.