This is a simply amazing find. It is right next to the Trevi fountain. From the rooftop outdoor area you can look 6 floors down on the throngs of people at the fountain while enjoying a quiet, relaxing evening away from the crowds.
Everything we wanted to go see was walking distance. The farthest (Vatican) was just a pleasant 45 minute walk. Colosseum was 15. Pantheon was perhaps 8 minutes. Spanish steps was 12.
There are so many fantastic restaurants in the area. Some are fancy, some are simple, all were wonderful food.
The host was super-responsive and always able to answer questions or arrange things like drivers.
The younger staff who let us in also helped with luggage. It is 6 floors, no lift. I am a professional photographer, and had a photo shoot during our visit, so I had a ton of luggage. The host sent two young men to help with luggage. That helped tremendously. The 6 floors is precisely 110 steps (we did it 3-4 times a day, so we counted!). So don't be afraid to ask for help with luggage when you check-in and out. That was for a small fee, but worth it.