I grew up in the ‘Bollenstreek’ where bulbs are grown on the poor sandy soil that was left after the sand of the inland dunes had been carried off to serve other purposes. Just outside the village of Hillegom is this characteristic bulb-barn with a flat roofed house in front of it. These barns were everywhere in this region (roughly between Haarlem and Leiden), and they were no more than very simple  brick squares, again with flat roofs.