This Colossal Dam Keeps Russia's Capital City Above Water

When Tsar Peter the Great founded the former Russian capital city of Saint Petersburg more than 300 years ago, he intended it to provide a "window on the Baltic." Turns out, that window was more of a screen door. To protect itself, the city built a dam that took almost 300 years and $3.85 billion to complete. » 9/09/13 2:00pm 9/09/13 2:00pm