The oldest but heavily modernized metro units in Milan are those of series 100, 200, 600 and 700. Production started in 1962 and continued through 1989 with many different manufacturers involved. They only operate on line M1 which is unique for its 3rd and 4th rail electrification system, similar to one of London's Underground. Interior and passenger doors are new and some other equipment, such as lights, were also changed. I like these trains quite a bit. Enjoy this short video. :)
English:
en.wikipedia.org/wiki/Milan_M...
en.wikipedia.org/wiki/Milan_M...
Italiano:
it.wikipedia.org/wiki/Elettro...
it.wikipedia.org/wiki/Metropo...