The following sets of directions have the Cadorna train station (a stop on the Ferrovie Nord, Metropolitana Linea 1 (Red Line) e Linea 2 (Green Line)) as their starting points. You can take via Carducci and then turn right onto Corso Magenta; if you continue straight on you will arrive at Sant'Ambrogio and the Science Museum (Museo della Scienza).
Otherwise you can take the green line of the metropolitana to Piazza Sant'Ambrogio and walk along via Carducci to arrive at Corso Magenta, or from Piazza della Conciliazione (Red Line), cross via Ruffini and you will arrive in Piazza Santa Maria delle Grazie, where you can find the basilica which houses The Last Supper by Leonardo da Vinci.