The mosaic shows a famous scene from the 'Metamorphoses', where Orpheus sings of love and a host of animals, enchanted by his music, gather around. It's much bigger than I expected, with far more animals, and better preserved. Definitely worth a visit. It's just inside the entrance to the university Chemistry Faculty. Walk in and you'll find a glass wall on your left, through which there's a good view of the mosaic. No charge.