A 19th-century floor mosaic of a bull in Milan's Galleria Vittorio Emanuele II is undergoing restoration after its testicles were worn down by tourists. The tradition involves grinding a heel on the mosaic for good luck.

Worn down by thousands of passers-by honouring an unusual tradition, a floor mosaic of an anatomically detailed bull in one of Milan’s grand arcades is getting a sensitive makeover. Legend has it that grinding one’s heel on the mosaic bull’s testicles at the Galleria Vittorio Emanuele II guarantees a return one day to the city. “Because of constant pirouettes on the heel made by tourists visiting Milan, the pink tesserae that make up its testicles have been worn down, forming a small crater,”...