This type is found outside the big train stations (north, central, south): http://s11.postimg.org/llbku67mr/image.jpg
This type is found throughout the city centre (Place Fontainas, Place Rouppe, Square de la Putterie, Porte de Hal, ...): http://s29.postimg.org/a0pc9i5av/image.jpg
These are perfect for beginners of graduated exposure therapy: the shape gives some privacy, there are always other people around, they're free, highly anonymous, ...
Also if anyone is in Brussels and wants to discuss paruresis in person with a half-recovered sufferer who has been to 3 UKPT workshops, e-mail me! :-)