The Cosmopolitan is only 5min. walking distance from Rome Termini station, which is a center of Rome transportation. So it cannot be better if you want to use Metro. The house is small but reallt clean and comfortable.
Especially, Francesco is really warm and helpful. On the arrival day, I got lost and it took one more hour than I expected. When I was in panic, he kindly let me know the way to get to his place. And then, he advised me how to travel Rome and let me know some of his favorite restaurants although it was late night. I will definitely choose his place again if I have a chance to come to Rome.
Grazie Francesco!