For me; there was simply one big reason to visit Belgium; beer of course! And we'd had our share, from great beer bars like Moeder Lambic and Dulle Griet, to a full on adventure (for me) of sorts; 
having a Westvleteren 12, which many claim to be the best, most coveted, and obviously the most sought after beer in the world, at In de Vedre, the cafe run by the Trappist Monks of Saint Sixtus who brew Westvleteren.
There was one last place for us to visit; the Holy Grail of Sours, Cantillon Brewery. And so we headed off from our apartment in Saint-Gilles. The Brewery is just a stop or two from Saint Gilles, close to the Gare du Midi Train Station. We however, (remember it's the Missus) walked.
Brasserie Cantillon is located in a somewhat gritty, industrial neighborhood, with a mix of various shops for different ethnicities. There's a huge empty lot across from Brasserie Cantillon, which seems quite low keyed.
There was no beer being made on the day we visited for our little self guided tour, but inhale and you'd get all the fragrances; yeasty-bready-sour-earthy…….
We went ahead and paid the 6 euros for the self guided tour; we'd been the first to arrive on this day, so Julie, whom I believe is the daughter of the Owner, was able to spend a good 15 minutes chatting about the building, the gueuze, and even the neighborhood. She explained that Cantillon still uses wild yeast and spontaneous fermentation, thus every year season's product is unique and different. The flavor she explained, "is in the building", we use no unnatural chemicals, our friends are the spiders who control the pests." The flavor is in the building. This isn't some shiny, bright and sterile, warehouse like structure in the middle of an industrial park…..the flavor is in the wood of the building, the breeze that comes in through the shutters. "Terroir" is a much used term these days……I had never really understood the concept as it applied to beer, until this day.
The tour itself was like travelling back in time, barrels of product…..aging for three years stacked along the walls and hallways.
Machinery, some going back to the 1930's are still in use……
For some reason, I found the walls of bottles mesmerizing….
I took way too many photos of bottles of beer stacked on one another.
At the end of the tour, you get a free drink. We decided to get whatever they had available for the day and a Gueuze Sausage, since it was still rather early in the morning and we needed some kind of sustenance.
Man, that unblended Lambic was super dry….so tart…..the finish was amazing.
The "Iris" had that nice "Cantillon sharp sour" tempered with a bit of hops and lemon-honey tones.
The gueuze sausage was better than expected; the texture of salumi, with sour tones like a good fermented sausage. Needless to say, it went well with the beer!
To me, Cantillon is a must visit when in Brussels, you are transported into the past, to how these types of beers used to be made. You walk freely along the hallways and equipment….there are no "keep off the grass" signs….they know you are here because you have an affinity for beer, they respect you, you respect them. And "le temps ne respecte pas ce qui se fait sans lui" – time does not respect what is done without him. 
In our day and age of instant gratification, it's nice to know, some folks still understand that good things often take time.
Brasserie Cantillon
Rue Gheude 56
Anderlecht, Brussels, Belgium