The Pantheon: is the best-preserved ancient building in Rome, and the largest unreinforced concrete dome in the world till recently.

The Duomo of Florence: is an amazing Church in Florence and well worth a visit.

Santa Croce: is a Church in Florence that has the tombs of some of the most famous people from history buried in it.

St Marks Basilica (and St. Mark's Square): is the center of the Venetian world and the Basilica itself hold the remains of Saint Mark.

Shopping in Milan: Go shopping in the heart of all design and fashion in Milan.

Cycling tours:
Several companies offer cycling tours of the Italian countryside. They provide cycles, a guide, and transportation for your suitcase, and for you if it all gets a bit too tiring. Tours vary to accommodate different interests. Normally you change city and hotel every day. If you like cycling this is an excellent way of seeing Italy off-the-beaten-track.