Marta's place is a quick 5 mins walk from St Peters Basilica. You cannot miss the basilica's dome whenever you step out. It was a safe area to walk around at all odd hours. We did a late evening long walk across all the major Rome attractions and landed at the Vatican around 2 am. Was absolutely fine walking back to the apartment. Pls do note it is quiet residential locality, so to dine you might want to go to Prati or Trastevere.