Headlamps prohibited in city center

I have seen that main or dipped beam headlights are not used at night in cities like Rome, with low wattage 'city lights' used instead in city centers. City lights are defined here as a small clear bulb inside headlight reflectors, used to define the presence of a car. They light up the headlight nominally using a 3-4 watt bulb to avoid glare in the eyes of other drivers where ambient light is sufficient to drive in dense urban centers. Can anyone provide an authoritative source on if and in which cities this is true?  Thanks!