When we travelled to Florence we had a half day to spare, so some of us took the train to Pisa and saw the Leaning Tower. We saw Galileo's original telescopes in the Science (history) Museum in Florence. We also stopped in Padua on the way to Venice. Galileo taught and worked at the University of Padua. In Venice we hit all the usual sights: Piazza San Marco, the Basilica, the Palazzo Ducale, and the Murano glass factory. We also visited the Museo Correr and the Archaeological Museum.
Milan was our last stop in Italy, and we had a tour of the Castle of Milan. It is a fortified castle, and in the museum we saw an original Leonardo da Vinci codeci (notebook). I'm all "museumed out", but the history and the art in Italy was just overwhelming.