Florence is considered by many to be an open-air museum. If you are interested in architecture, for example, you don't need to visit any museums: many of the palaces and squares are masterpieces of their own.
Designed by Michelozzo, Andrea di Cambio and Brunelleschi, among many others, many of the great palaces and piazzas in Florence are spectacular to behold. The main squares often display statues by Giambologna or Michelangelo. Ponte Vecchio, Old Bridge, is a treasure to admire.