A good idea if you want to visit Padua is to buy a "Biglietto Unico" (one Ticket), valid at most of the museums in Padua and good for one year. Theres also a ticket for the monuments and museums in the province. You can buy both of them at all the monuments and museums that they give access to and at the tourist offices.
Well now take a look at one of the symbols of this city: the 'Palazzo della Ragione' ...