I gathered this much from Google and my rough (very!) French:
Journée du patrimoine: European Heritage Days, celebrated at various places in many countries. In France, it's the 3rd week in September. Seem like fun actually, lots of free visits to museums and art galleries and such.
This one was a "tango walk-about" in the town of Lille (mairie-lille.fr), by a school of visual arts, in the old part of town.
> Déambulation Tango
Dimanche à 14h (durée : 1h)
Déambulation dans le Vieux-Lille accompagnée par deux géants dansant le tango nuevo. - Départ : Vieille Bourse
Note the reference to tango nuevo!
Correction: Lille is a district (county? city?), Vieux-Ville is a town/community/neighborhood. Hey, it's only less than 1 hr from Brussels by train. I might go there next time I go to Belgium to visit my family.