België, de kust by Léo Marfurt, 1938
Hungry beary by Elisabeth Ivanovsky, 1956
Antwerpen by Lucien De Roeck, 1934
Belgian National Railways by Herman Verbaere, 1948
La libre Esthetique by Gisbert Combaz, 1899
Le Sillon by Fernand Toussaint, 1895
The Veerle blog has a great post celebrating Belgian graphic design — these are just a few of what they're featuring (along with nice mini bios of the illustrators and artists, too). Have a look at more beautiful vintage work on their site here. Via brainpicker.