The biggest photo in the world is an 80-gigapixel panoramic photo of London, made from 7886 individual images. This panorama was shot from the top of the Centre Point building in central London, in the summer of 2010.
Paris : 26 GigaPixels
Dresden : 26 GigaPixels
Prague : 18 GigaPixels
Budapest : 70 GigaPixels
Check out the website, where you can zoom in on the photo to see the full detail - you might even be able to see your own house!