Revolution rarely happens in IT. When it does, we typically deal with disruptive moments that come suddenly and are often unexpected. For the majority of the history of IT, however, we are seeing a much more evolutionary process of technology that happens over time. The data center and its history may be one of the best examples to describe this mix of revolution and evolution as new computing models develop with new technologies and opportunities over time. This is the history of the computer systems that have lead computing at the very high end in their time.