I can't remember anything we were told there, but many Hungarian houses (in the suburbs and out in the country) don't have a basement, so the transformer serving the entire house had to be put somewhere in the living space. The idea didn't really catch though.
Budapest had the electrical distribution built by two companies, downtown was wired by the Austrian Edison Company which of course used DC. Everything else was wired by Ganz, the Budapest based Electrical plant, whose founder was one of Europe's AC pioneers and inventor of new transformer types.
The museum was once a large rectifier station built in the 1920s, later a transformer substation.
Vienna had a similar mix of power systems, the mainly residential areas were wired for DC; the industrial areas had AC as early as 1903 (3 phase AC, probably 127/220V). The last DC supplies were converted to AC (220V three phase wye, though no neutral wire supplied, only bonded to ground at the transformer) in 1955. Throughout the 1960s and 70s these 127/220V supplies were converted to 220/380V 3 phase wye with neutral.
