The Palazzo Grassi is owned by the Fiat auto company (or to be confusingly precise, was, is they sold it a few years after our visit). It's used to host special events and exhibits, and by coincidence it was holding a special museum exhibit about the Egyptian Pharoahs that was getting great reviews from all over the world. We tried to visit the day before, but the line was about a mile along so we gave up. Today, as we were walking back toward piazza San Marco to get the boat back to the hotel, we passed Palazzo Grassi and not a soul in line. I assumed it was closed, but we pulled on the door to check and we had the place pretty much by ourselves. I have no idea why the attendance was so variable, but we really enjoyed the exhibits and spent a couple of hours there. If we had managed to get in with the crowds yesterday, I think I would have been out of there in ten minutes flat.