Understanding the World's Greatest Structures Season 1 Episode 22 Vast Roof Systems of Iron and Steel

The need for roofs spanning large enclosed spaces led to a startling number of new structural systems in the last 200 years. Look closer at long-span structural configurations in places such as the Houston Astrodome, the Berlin Hauptbahnhof, and even the Hartford Civic Center (the collapse of which offers a lesson in the risks of innovation).