Unfortunately the museum is currently closed for restoration, or so the story goes.
This is what the books say about the museum:
Roman Museum - The museum is a must, and has an extensive exhibition of everything from statues of a winged Victoria writing on a shield and flanked by two barbarian prisoners begging for mercy in the courtyard to small coins. In the western wing you will see objects unearthed from the tombs here. Other wings display some wonderful mosaics from the Basilica of Justinian, including a vividly coloured peacock, mosaics from Oceanus’ baths, statues from the Temple of Zeus, ornate frescoes from a private house and a well-preserved mosaic of nymphs grooming the mythical Pegasus.