Prussia
Prussia was scattered throughout current day Germany, Poland, and Kaliningrad, Russia.
Overlay map of Prussia and current day Europe
Click the above link and you will be taken to an interactive overlay map of the 1760's map and the present day map behind it. In the upper right of the map, you will see a slider which will allows you to slide between present day to the older map. A nice feature is the ability to zoom in and out between the two maps.