One of the undoubted highlights of a trip to Bruges is the Belfry, a huge tower which dominates the skyline. With 366 steps, this isn't a climb for the faint-hearted, but it's well worth it if you can. Although it can get a bit hairy when you meet people coming the other way on the narrow stairs, there are a few rooms where you can stop for a breather.
The 47-bell carillon is an incredible sight. You can get close to the drum, which is regularly reprogrammed to play a different melody, and if you time it right you can also catch the bells in action.
The view from the top is also pretty spectacular.