There is a fantastic garden in Florence, right near Piazzale Michelangelo, that is open for just a few weeks of the year and features thousands of varieties of Irises (over 1500 to be specific, including 15 that risk extinction). It’s the aptly named Giardino dell’Iris, accessed from the East balcony of Piazzale Michelangelo, free to enter, and with impressive views over the city. Needless to say, it’s a photographer’s heaven!
For spring 2010, the garden is open April 24 to May 20th.
Here’s a flickr gallery of previous Iris garden years (this year I haven’t managed to go thanks to the constant rain!).