The Milan Metro (Italian: Metropolitana di Milano) is the rapid transit system serving Milan, Italy, operated by Azienda Trasporti Milanesi. Milan metro is the longest metro system in Italy. The network consists of 4 lines, identified by different numbers and colors, with a total network length of 92 kilometres (57 mi), and a total of 101 stations, mostly underground. It has a daily ridership of 1.15 million.
The first line, the red one, opened in 1964, making Milan the second city in Italy after Rome to have a metro system. The green line opened 5 years later in 1969, the yellow line in 1990, and the lilac line in 2013. Current expansion of Line 5 and part of the new Line 4 are planned to open before the 2015 Expo.
The Province of Milan (Italian: Provincia di Milano) is a province in the Lombardy region, Italy. Its capital is the city of Milan. The provincial territory is highly urbanized, resulting in the third highest population density among the Italian provinces with more than 2,000 inhabitants/km2, just behind the provinces of Naples and the bordering Monza e Brianza, created in 2004 splitting the north-eastern part from the province of Milan itself.