Tibetan Buddhists can spend 7 to 10 days making an intricate sand mandala like the one above. The mandalas usually represent an imaginary palace that the monks think about during meditation. Once the monks complete the mandala, they destroy it, demonstrating that nothing is permanent and that attachments only lead to suffering. The Huffington Post has a short story explaining how this picture of the mandala went viral after an original posting on Reddit. They also have a nice slide show of mandalas around the world. You can learn more about how they make them at this BBC Religion site.