Xanadu. You have to admit that X is a really hard letter to come up with photo for, so this is the best I can do. Xanadu means an idyllic, beautiful place. My first thought was to find a photo of somewhere idyllic and beautiful and just call it Xanadu...instead I did this.
If you have a better idea for an X photo, then click on the image below and put your own up there :)