Fontana di Apartment is a beautiful flat superficially, but with some issues which make it a little difficult. The key situation is one: it is necessary to turn off the electricity switch on the wall when leaving the apartment (the keys are all padlocked together). Thus if one person wants to leave, either the one left has no electricity, or the two have to coordinate getting back in as there is only one key. The second person could leave, but not get back in without this coordination.
The flat didn't smell superclean, the towels were a little dingy, and the kitchen was difficult to use. There are a lot of stairs, but we knew that in advance. The place is beautiful and in a great location, just steps from the Trevi Fountain.