Vienna: Some districts had 127/220V AC (probably) in 1903, others had 220/440V DC until 1965. As far as I know DC had the same round pin outlets as AC had later. From the 1950ies on (maybe earlier) the remaining areas were converted to 127/220V AC, others to 220/380V. The last 127/220V systems were converted in the late 1970ies. 127/220 meant the customer just got 2 phases of a wye system and no neutral. Large houses got all 3 phases. In Berlin 127/220 still exists but is supposed to be phased out this year. The customer didn't see much of a difference, except for having 2 phases when sticking a phase probe into a receptacle. Naturally polarization was completely useless with 2 equal phase conductors, so there wasn't any color coding.
