Line C of the Lyon metro is fifty years old and its operator, SYTRAL Mobilités, has commissioned an original mural to mark the occasion. It will be permanent fixture which will be the backdrop to an illuminated projection during the Festival of Lights. This rather special mapping traces lines and circuits and we can guess that the marbles represent[I1] the flow of passengers. The criss-crossing rails and lines symbolise the back-and-forth of our daily commute. The multidirectional lines, like the warp and weft threads on a loom, remind travellers of Lyon’s silk-weaving tradition and the extensive network beneath our feet.