<p>Italy's Sforza Castle includes a underground passage that linked the Duke of Milan to his wife’s tomb.</p> <p>The post <a href="https://www.popsci.com/science/da-vinci-castle-tunnel/">Da Vinci was right: Secret tunnels found in Italian castle</a> appeared first on <a href="https://www.popsci.com">Popular Science</a>.</p>