By my count this year marks the fiftieth birthday of the field of computer-aided design. It is, therefore, an appropriate moment to look back on how the field has developed in its first half century and then to consider what we might expect in the coming decades - the decades that will see the continued development of what I have called the City of Bits. The story is, as we shall see, one of shifting intentions, at each stage in the evolution of computer-aided design, the technology has found niches in practice determined both by its capabilities at that particular historical moment and by prevailing economic and cultural imperatives.