FLORENCE— The Florence International Antiques Fair — held in the beautiful 17th-century Palazzo Corsini on the bank of the Arno River — certainly has plenty to offer in terms of ambience. Add to that 90 dealers bringing a superb collection of paintings, European furniture, maiolica, medieval and Renaissance works of art, and Italian sculpture, and the result is a spectacular event. The nine-day fair, which held a vernissage on Sept. 25 and is open to the public through Oct. 4, is the most important in Italy, drawing huge crowds of locals and enthusiasts from countries including the United States, Switzerland, and Germany.