Since the Travelling Salesman problem is a NP-hard problem, it's a good example on how to use a GA. When you're unfamiliar with GAs I recommend checking out my talk on GAs.
In this case there are 15 cities and their distances are hard-coded in an array in the code.
You can change the population's size and the number of generations in the form to the right. After the maximum number of generations is reached, you will see a performance chart of the current run.