Now you can find maps of the attractions, “The baths pf Caracalla” and “The Catacombs of San Callisto”. Both of them are interesting places to visit when in Rome. At the baths och Caracalla you get impressed of how big the ancient bathouses was ( Bath of Caracalla was the second largest bath in Rome). In the Catacombs you can get a mixed experience, both a kind of creepy feeling in the cold crypts surrounded by tombs but also a reverent sense knowing that many saints and popes is buried here.
This is a common trip for 10-14 days. I pefrer more time in each city/country, but I am a student (ie. no job) and live in Europe, so my experiences aren’t really applicable to this situation. What I can say is that many of my American friends have done similar Italy+Greece trips and have had an amazing time. To get from Greece to Italy, taking a ferry is the most common option, albeit a rather slow method of transportation. You can do further research in to ferries from Greece to Italy here:Basically, this is how its done: From Athens, you take a bus or train to Patras. Another option is taking a bus to Corfu/Igoumentisa (an island accessed on a bus via a short ferry crossing). Patras is closer to Athens, but Corfu/Igoumenitsa are closer to Italy. From either port (on Greece’s west coast), take a ferry to one of the many ports on Italy’s east coast. Italy’s main ferry ports on this coast are Bari, Brindisi, Ancona, and Venice. Brindisi and Bari are the closest to Greece, Venice is the farthest. From any of these ports, take a train to Rome or wherever else you want to go.The Italian National Railway website is here:Honestly, you could stay in Italy for the whole trip. Or Greece, really. 11 Days seems so short for both. There is so much to see and do. I hope this helps.