The last of his books to be published during his lifetime, Turris Babel was Kircher's attempt to reconstruct the specifics surrounding the famous biblical story, recounted in Genesis 10-11, of Nimrod's attempt to build a tower that reached the heavens. Apart from his interest in ancient civilizations and biblical historicism, the story was of particular interest to Kircher as an account of the origin of languages, and, by Kircher's extension, of polytheism. The second half of Turris is devoted to Kircher's theories on linguistics. The first section, similar to his Arca NoŽ of four years earlier, contains an imaginative speculative expansion of the Tower of Babel story in light of Kircher's knowledge of history, geography, and physics. This model illustrates Kircher's proof that Nimrod's ambition was intrinsically flawed: in order to reach the nearest heavenly body; the Moon, the tower would have to be 178,672 miles high, comprised of over three million tons of matter. The uneven distribution of the Earth's mass would tip the balance of the planet and move it from its position at the center of the universe, resulting in a cataclysmic disruption in the order of nature.