The gigantic circular painting (110m circumference and 10m high), painted by Genevan Édouard Castres in 1881, is one of the most spectacular examples of 19C panorama paintings, which were famous attractions from before the cinema era. It illustrates an episode of the Franco-Prussian war (1870-1871), which is also evoked in the Bourbaki Museum. The old rotunda, built to house the painting, is now encased by a glass frame and houses a cinema, the public library and shops.