While we were travelling through Europe, the sign that a building was truly old was that it was covered in scaffolding. Sure, these buildings really need their maintenance, but it's kinda annoying. I don't think I've seen Notre Dame scaffold-free, ever. Ditto St Pauls.
Enter computer scientists James Hays and Alexei Efros who've got a great paper detailing an amazing system they've built. You can chop a chunk out of a photo and it will replace it seamlessly, drawing on a large database of photos taken from the net. Also works for annoying tourists walking through your carefully lined-up photo. Brilliant!