Modern synthetic chemistry has equipped researchers with the ability to construct molecules of ever increasing structural complexity. In some ways, synthetic chemists can be likened to architects or engineers working in a molecular world. This analogy is more appropriate then with respect to the current endeavor to design and synthesize molecular machines since chemists, like architects, must consider
design, construction, and interactions with surroundings. This chapter will explore the realm of synthetic molecular machines by highlighting the design, construction, and function of a number of examples in the fields of rotors, muscles, switches, etc., where the common theme is a change in material properties as a result of some stereochemical rearrangement at the molecular level.