This apartment is very very close to the Coliseum. And It is about 40 minutes walk to Fontana de Trevi. The metro is nearby and can bring you anywhere you like in no time.
We saw Vincenzo a couple of times, always very nice and ensuring that we were fine.
Make sure to check in before 9pm as there is a charge for late check-in.
A must : try Da Francesco pizzeria while in Rome.