In looking for a natural tiling that doesn't repeat squares, one quickly discovers that the first five squares fit together neatly (Figure 4) but it becomes progressively more difficult to add consecutive squares without overlapping or leaving gaps. This suggests the following question: Can the squares with whole-number sides, one of each size, be fitted together to tile the plane? The answer is that they can. In succeeding sections we will prove this, discuss the history of the problem, and pose a number of questions.