We contacted the number which we got from Roberto and the response was really quick. We were traveling with our bus and parked on the street right in front of the apartment. (4€ - 8hours) The host of the apartment already waited outside for us and welcomed us. The apartment itself is really close to the colosseum and the city in general. We either walked around or took a scooter. (Really easy to log in and a cheap version to get around) The apartment was really clean and everything was perfect. If we come back we would try to get a room at Robertos again. :-)