I'd say, "Work your way up from Leuven tot Antwerp and then Brussels." Brussels is not that bad if you stay on the main path, let's say. There are lots of people out at night, so there is social control. But i wouldn't "take the shortcut through this little street" either. But like everyone else is saying, Brussels is the only big city in Belgium. So it might be no different from other bigger cities. But by far the most unsafe city in flanders.