Various lists of the wonders of the world have been compiled over the years to catalogue the most spectacular man-made constructions and natural things in the world.The seven wonders of the ancient world is the first known list of the most remarkable man-made creations of classical antiquity, and was based on guide-books popular among hellenic sight-seers. The number seven was chosen, as the Greeks believed that it represented perfection. Many similar lists have been made, including lists for the medieval world and the modern world.