Originally Posted by Zinc_Saucier
Go to the Cantillion brewery as well as Delirium Cafe when in Brussels.
An enthusiastic co-sign on both of these.
If you're looking for a good bottle shop as well, I enjoyed Beer Mania:
My wife and I got to talking with the owner, who was really friendly - turns out he's a brewer as well, and sells his beer in the shop (sort of a golden strong, if I remember right). Back then (~5 years ago?) it was just in a plain unmarked bottle, but it looks like they've stepped up the branding a bit. He also has a crazy-looking custom glass he serves it in.