Milan has 4 subway lines: one (the red line), two (green line), three (yellow), five (lilac). Plus all urban rail lines that cross the towns. You might ask what happened to line 4. Fair question. Starting now to be built. Here, first pictures.
PS. Here is how it works in Milan. Next line will be line eight. Then line seven will see the light (no, it won’t really see the light, it’s just a way to say that it will go live). Finally line six will be completed, after the inauguration of lines seven and eight and the start of works for line ten.