The second-largest Italian city in population (after Rome), it is a leading commercial, financial, and manufacturing city and a major centre of intellectual and artistic life. Milan is predominantly modern, surrounded by industrial suburbs. It has many tall apartment and office buildings in the business district and extensive residential and industrial sections. An underground railway was opened in 1964.
The principal square is the Piazza del Duomo, at one end of which stands the Duomo (cathedral) a huge Gothic structure of white marble, begun in 1386 and completed in 1965. To the south-west of the Piazza del Duomo is the basilica di Sant'Ambrogio (AD 386). Near the basilica is the 15th-century church of Santa Maria delle Grazie. Adjacent to the church is a former Dominican monastery, in the refectory of which is the famous fresco of the Last Supper by Leonardo da Vinci.