This question was posed in an earlier Design Appreciation lecture and for weeks, I have been struggling to find the answer myself. At first, I was telling myself a design was only good if it had a pleasing appearance and function. It was not until recently in one of the last lectures that I came to understand that a good design can be something that can continuously be maintained throughout time and possibly even gets better WITH time. A great example of this type of design is Landscape Architecture. While the layout can change appearance and continue to flourish, the original intent is never disturbed and also has a positive impact on the environment.