If you want to go out and have a casual evening with friends, Navigli is the place. It’s a district south-west of the city center easily accessible by tram or metro. Navigli is characterized by canals, along which you’ll find a lot of bars and restaurants. It's the most vibrant and diverse area in Milan and the evenings are full of life even on weekdays.
Navigli refers to a system of Milanese canals, which used to be interconnected and important for transportation. The two main canals are Naviglio Grande and Naviglio Pavese. On these two you can still catch a sightseeing boat or have dinner on a restaurant boat. Both canals connect with the Porta Ticinese dock, also known as the Darsena (which is also nice nowadays after the Expo-renovation).
But enough of geography and history, the reason you’ll want to go to Navigli is the bars and restaurants and all the fun. You won’t find many clubs in Navigli, but there are plenty of nice places for enjoying an aperitivo or having a real (but casual) dinner.
The concept of Apritivo has evolved to something special in Milan. Literally aperitivo means an alcoholic drink consumed before dinner to stimulate the appetite, but today it's much more than that. In addition to a glass of wine or a cocktail you'll typically find a buffet with a wide selection of antipasti and primi. If you go the whole nine yards you won't make it to dinner. No surprise that this is a popular strategy among students. The price of a decent aperitivo will be between 5 and 12 euros. You should pay over 20 euros only at Bulgari or Armani.
A cool aperitivo place is Ginger Cocktail Lab, not only because they play Kraftwerk, but because it's a cozy bar and they serve a fantastic selection of small dishes, many of which are suitable also for vegans. If you’re interested in sushi aperitivo, check out Ristorante della Nonna, which despite its name is an Asian fusion kitchen with a great sushi selection.
There are a number of great restaurants along the canals but my favourite is Al Pont de ferr. It’s a highly experimental and super sophisticated kitchen, so prepare to be amazed. Not too expensive and above all, the food is excellent and the wine selection is exquisite.