You may have noticed but on many maps there are lines and borders on them that you can’t see or find when you are at these locations on the ground. While true in the visible sense, if you were to go to court in a legal case to find the border of someone’s property or you wanted to find the prime meridian, there are tools to help you find these invisible lines. You can use your GPS to find one of the more used lines that exist on maps but aren’t seen on the ground. These are the lines of latitude and longitude. These lines will be particularly evident if you have several people each with their own GPS unit.