It’s like the orange madness, only in primary colours. It is in every city in the Netherlands. Everywhere. You can’t turn a corner without bumping into a red-white-blue and yellow & black decoration or object. It’s what happened to me. I was in Leiden for my regularly city walk. Walked through the city centre, into one of the historical streets. Turned the corner and there it was: a De Stijl open air museum Leiden.