Measuring and understanding time has been a concern for the human race since before recorded history. Whether it is on the scale of years – knowing when to plant and when to reap, when the rains or floods should arrive – or on a smaller scale, being able to distinguish when events occur during the day and relate them to an accepted means of measurement, the ability to record and measure the passing of time, has always been important. With measurement came visualization, communicating the measurements from one person to another. This chapter looks at how time has been visualized over the centuries, selecting representative or important examples and discussing them not primarily for their historical content but for what we can learn from them in our overall goal: to display data in a way that leads to action. The great advantage of studying historical visualizations of time is that the goal of actionability was always at the forefront of the designers’ minds. Unlike now, when graphs and charts can be created with ease, previously the creation of a visualization was a time-consuming proposition, and so the charts we see had a solid purpose to them. Another advantage of studying historical visualizations of time is more Darwinian in nature: Bad visualizations have not generally survived the centuries, and so we are left with the cream of the crop from which to learn.