This public museum is an archaeological treasure trove. Situated beneath the 4-5th century Church of St John and Paul lies a complex set of dwelling houses dating back to the second century. These were rediscovered in 1887 and excavated over the following years.
The earliest building is a single house, or domus, which had its own bathhouse. This was followed by an insula - a block of flats built for renting out to multiple occupants. A third phase saw the structure once more became a single residence. Remains include some fine mosaics, superb frescoes and original vaulting. Artefacts discovered during the excavation are on show in the museum.
When the Church above was built, the Roman dwellings became the foundation and crypt. Most traces of the opulent decoration were lost although some rooms were used as storage for an extended period.