What's that on the map?

I was looking at a map of the city centre. I'm sure there is a cut-through to the library to avoid having to go down the main road and over the bridge. I wondered what the 'compass point with arrow' was on the screen. It was puzzling me because it was on a blank bit of map. A colleague suggested I move the mouse to see what happens. It was the mouse pointer. I felt so embarassed.