For me, no trip to Florence is complete without a trip to this Basilica. I know, you're in Italy and there are a thousand Churches with exquisite paintings and sculptures. So what makes the Basilica of Santa Croce different?
Florence is the cradle of the Renaissance and in the Basilica are the above ground crypts of some of the greatest artists and thinkers of this time.
Highlights are the crypts of Michaelangelo, Rossini, and Galileo (even though Galileo is buried elsewhere) and many others. They are all phenomenal works of art but the crypt that always brings me to tears (even now) is Dante's - with 3 sculptures above his crypt: one representing Italy, one representing Art and the third, bent over in anguish is Literature.
Do yourself a favor and visit this Basilica.