The most fascinating thing with Galleria degli Uffizi in Firenze was its architecture, stunning hallways with the most amazing ceilings. Impressive.
I had booked tickets in advance, which limited our time in line. Furthermore, I planned our visit for 15-18 in the afternoon, i.e. during some of the hot hours, and this turned out to be great plan (except for that it still was 36 degrees at 20 in the evening).