Rome is excellent for walking, with sites of interest often clustered together. Much of the inner core is traffic-free, so you'll need to walk whether you like it or not. However, in many parts of the city it's hazardous and uncomfortable because of the crowds, heavy traffic, and narrow sidewalks. Sometimes sidewalks don't exist at all, and it becomes a sort of free-for-all with pedestrians competing for space against vehicular traffic (the traffic always seems to win). Always be on your guard. The hectic crush of urban Rome is considerably less during August, when many Romans leave town for vacation.