The main cycle race in the region.
The main day has been held in Cassel for several years, and attracts a large crowd, so parking is moved outside of the town.
You can follow the whole race on big screens whilst soaking up the atmosphere in many of the local bars/restaurants around the main square.
It would be advisable to book a table in advance if intending to eat, or alternatively pick up some take away Frites (PMU and Chaumiere allow you to eat them on their terrace).