Still, iron was the first material to let people build truly tall buildings. The Eiffel Tower, for instance, is actually built out of wrought iron. Wrought iron is strong, but also inconsistent and prone to flaws that are impossible to detect until a particular piece fails catastrophically. This is something that happened regularly throughout the nineteenth century, causing factories to collapse on the heads of the workers below and trains to derail or fall into rivers when the bridges they crossed collapsed. Steel, in comparison, is much more consistent, and as soon as people figured out how to make it in large quantities they began using it for everything. In fact, when people say “wrought iron” in reference to fencing, what they are probably referring to is steel fencing that looks like wrought iron. The confusion might also come from the fact that steel is really just iron worked at higher temperatures to ensure an even distribution of carbon.