Palazzo Grimani is a Renaissance palace near Santa Maria Formosa, now used as a civic museum. The rooms are worth the visit as much as the collections: painted ceilings, carved stonework, and classical details show the taste of one of Venice's powerful patrician families.
Inside are paintings, archaeological pieces from the Greek and Roman world, and temporary exhibitions. It is quieter than the big sights around San Marco, which makes it a good stop when Castello starts to feel crowded.