Milan Cathedral (Duomo)

If you only have time to see one sight in Milan, this would be it. Milan's Duomo is, after all, the world's fourth largest, taking half a millennium to build. Begun in 1368, the breathtaking Gothic cathedral can hold 40,000 people; so even with peak season's crowds, this attraction will feel pretty empty. Although there's much to see, we highly suggest you 1) spend some time staring at the beautiful stained glass and 2) head to the roof for a walk among the buttresses, statues and pinnacles, plus a great view of the city below.

A Virtual Tourist user says this: "I have to confess, all the churches, including the unbelievable Basilica di San Marco in Venice, I visited after the Duomo, [cannot] really compete against its splendour." One TripAdvisor user offers this advice: "It is best to do a tour to get all the informative details regarding this landmark. After visiting the Duomo, take time to stroll over the piazza to the Galleria. It is beautiful."

The Duomo is free to visit, but there are smallish fees (less than €10 EUR) for touring the roof, crypt, baptistery and museum each. You can visit from 6:50 a.m. to 7 p.m. daily. However, both the baptistery and the museum are opened for shortened hours Tuesday through Sunday. You'll find this church just off the Duomo metro stop. For more information, you can visit this website.