Alon, In a city with a metro system, each trainset should be painteed a separate theme, both for the art and for passenger recognizability ("I lost my bag on the train with the sunflower scenery"). If the lines have separate fleets (as in Paris and London but not Berlin), then the art could even be color-coded, so the Central line gets paintings with reds, the Piccadilly with dark blues, etc. What are some examples of themes for such painting?
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