PGR3 ships with a built-in Route Creator, allowing you to create your own circuits in any of the five cities. You'll find the Route Creator option under Playtime from the main menu.

Using the Route Creator is easy. Once you find yourself in a screen similar to the above, just hover over one of the chequered flags and press [A] to place your starting position. Then continue to connect the circular points together until you've made a circuit. Alternatively, you can link up to another chequer flag to make a point-to-point race. Once your route has been saved you can play it in Playtime mode, both offline or online with friends.