This was Tanks in Town weekend. A procession of tanks pour into the centre of Mons to commerate the liberation of the city by the allies in 1944. It was a really nice and fun (if that's the appropriate word) occasion.
At first everyone is kept behind barriers whilst each and every armoured vehicle enters the Grand Place. Once they were all in, you were able to walk around and inspect and touch them. You could also chat to the people driving them. Judging by their appearance, safe to say that no one there was actually involved in the war. I guess there comes a certain age when driving a tank is probably no longer deemed safe.