Leonardo da Vinci is known for his paintings such as the Mona Lisa and The Last Supper. But did you know that Leonardo also had interests in sciences and in engineering? Check out his blueprints of various weapons like cannons and ballistae in his Codex Atlanticus, which can now be read online. The codex is a 1119-page collection of papers.
You can read the digital scan of the Codex Atlanticus online at this link.
(Image Credit: Kottke.org)