Koolen has made several large wall paintings: worth mentioning are Brand Bierbrouwerij (Brand Brewery) in Wijlre (1937), the building of the Air Staff in The Hague (1956), the Abbey of Middelburg (1957), the Campina Dairy in Eindhoven (1960) and the post office PTT (1967) also in The Hague. Some are unfortunately lost including the mural in Middelburg.



Left to right: Abbey Middelburg, Brand Brewery, Air Staff, Campina Dairy

See for details the links below