Second to the Uffizi like Florence is second to Rome. Even though it’s south of the Arno, the Pitti Palace is a great place to visit. The Palatina Gallery has great pieces by Correggio, Raphael, Titian and Rubens. It has also kept it’s palacial interior so walking through the galleries gives you a much better idea of how the Medici lived than the Uffizi.
The Boboli Gardens are right behind the Palace.