Arab historians had claimed for centuries that the Great Pyramid had been used for astronomical observations, yet no one could prove that such could have been the case, for the Great Pyramid's smoothly polished limestone sides made it inaccessible to potential star-gazers. Then, just before the beginning of the twentieth century, a British astronomer by the name of Richard Anthony Proctor released a book with an explanation as simple as it was logical. The Great Pyramid, he suggested, had functioned as an observatory before the top was completed, allowing the Grand Gallery to be open to the stars, and thereby function as a very effective (and large) telescope.
