Google released a research paper on landmark recognition technology (think: Statue of Liberty, Eiffel Tower) at Computer Vision and Pattern Recognition (CVPR) conference in Miami, Florida, enabling computers to quickly and efficiently identify images of more than 50,000 landmarks from all over the world with 80% accuracy. “First, we generated a list of landmarks relying on two sources: 40 million GPS-tagged photos (from Picasa and Panoramio) and online tour guide webpages. Next, we found candidate images for each landmark using these sources and Google Image Search, which we then "pruned" using efficient image matching and unsupervised clustering techniques. Finally, we developed a highly efficient indexing system for fast image recognition,” explained Google.
Download: Google Landmark Recognition (PDF)