RedmineRoadmap » History » Version 2
If you select the Roadmap you will get an overview of the current state of your project, like the following:
There you can select which issues are open and which are closed. If you are interested into a detailed list of which issues are not solved you can simply click on to the number left to open, but if you like to know which issues are already solved simply click on the number left to closed. The green bar will indicate how far you away from finishing your milestone (98%).