This is for Sandra (her blog is A Journey of a 1000 Miles), who "collects" Annunciations and will be able to add this one to her collection when she returns to Venice this summer!
So when you are looking at the side of the bridge shown in the photo above, Archangel Gabriel is on the San Polo side and the Madonna is on the San Marco side. I had a photo of the angel but not the Madonna (I found her on Wikipedia).
This isn't the only Annunciation scene on this bridge; I'll post the other one tomorrow.
Happy St. Patrick's Day!