St. Mark's Square is wonderful, but in the early morning before everyone gets there is the best time to visit. Like 6am is the best. I was there during a very hot time of the year. I have been there during October of the previous year and the weather was much nicer. Summer is just very hot..... But the square itself is very nice, lots of shops. With masks that are made in Venice and hand blown glass shops. It is a sight to see. Do not go to Italy without going to Venice. It is a must.