We never know Guilio's apartment is 500yrs old till we saw the wooden beam & columns. It's the best house we ever had - spacious, well decorated & equipped.
Walking distance to major attractions and saved us from Christmas Day without mid-day public transport.
Trastevere is a great area to stay and much, much safer than other side. It's vibrant residential area with loads of old churches and nice restaurants - you could even found a Bar opening in Christmas!