In Belgium, yes...but there were earlier (and very well-known) casinos in Europe prior...way prior, especially in Venice: La Serenissima (1625)....and even as far back as the 12-Century. They were not called casinos that far back...but they were organized gambling dens with all sorts of good stuff going on while masks were worn by those who visited. <g>

Spa is the oldest remaining casino in operation.

JB