Eurail for Portugal / Spain / France / Italy

I believe there are many cities and towns in Southern France will be suitable for your needs because there are many Roman ruins in that areas. For example, Avignon, Arles, Aix en Provence, Gordes. All of them are famous for their historical buildings.
Your trip in Italy will be a long trip, I believe you have to spend at least 1 month for it. But please be reminded that Malta is not a part of Italy. It's an independant countries lying on the Mediterreanean Sea. From memory, Capri should be a seaside town, it may not fit your aims.
In my opinion, I will choose Northern France (Paris and Normandy) instead of Southern Italy because there will be more attractive spots in Paris and the historic building in Normandie are also very famous. Also, you can think about Corsica island as well.
If your schedule is fixed. Then you have to count how many train journey you need to travel

Lisbon to Madrid
Madrid to Barcelona
Barcelona to Marseille
Marseille to Milan
Milan to Venice
Venice to Florence
Florence to Pisa then to Rome
Rome to Naples
Naples to Capri
Capri to Palermo
Totally you need to travel on train for 10 times. So, you can consider buying a Eurail Select Pass (4 countries 10 days in 2 months) for your trip.