Strike on Thursday Dec 22 - public services (Brussels)
A word of warning: there will be new union actions this week on Thursday Dec 22, as a consequence to the new pension plan being voted by the (new) government. I heard that some train services are already affected today (Tuesday), but especially on Thursday you need to be careful. This is a general national strike day, but hopefully limited to public services. This means: public transport (for sure, they're always the first to strike), communes, trash collection, etc. Be careful: trains will probably already start their strike on Wednesday evening, usually around 10 PM.
Even the airport and schools might be hit, so if you have kids going to public schools get informed. Hospital services might be affected as well. The "nice" part is that this is a last minute action, so the unions don't even know themselves which services will be affected... If it's a public service, count on trouble, I would say.