Swapping in Belgium, Luxembourg, Netherlands personally + flea markets

Hi to Numistas from Belgium, Luxembourg & Netherlands
due my August vacations there would be great to know if there are kind of interesting coins shops and flea markets which is useful to visit

+ able to meet & swap in person to skip the post routine and for fun
cities: Luxembourg, Brugge, Ghent, Brussels, Antwerp, Dinant, Leuven, Rotterdam, Den Haag, Delft

just send a PM