The Domus del Chirurgo, the Surgeon's House, is a small but exceptional archaeological site under a glass canopy in the middle of Piazza Ferrari. You walk on raised gangways across intact Roman mosaic floors, including the famous Orpheus mosaic showing the musician charming a circle of beasts.
Combined ticket with the adjacent Museo della Città, where the surgical instruments themselves are displayed alongside the broader Rimini archaeological collection. Allow ninety minutes for the pair.