The Milan Metro Line 3, (Linea Tre in Italian), is a subway line serving Milan, Italy. The line is part of the Milan Metro and is operated by ATM. Construction began in 1981 in order to be ready for the 1990 Football World Cup. It is also called the Yellow Line (Linea Gialla) as it is identified by yellow signage.The line connects the south-eastern suburb of San Donato Milanese to the north-western area of the city passing through the city centre.