New industrial processes began to have a big impact on architecture towards the end of the 18th century. Architects began constructing buildings around huge frameworks of iron, rather than natural materials such as timber, clay or stone.
For the Natural History Museum, Alfred Waterhouse used a combination of cast iron for the columns and a mesh of wrought iron for the floors.
Wrought iron made the challenge of bridging wide spaces like the Central Hall a possibility, because of its flexibility and strength under tension. The rivets that join the different sections of wrought iron are just visible today. The same technique was used on many mainline railway stations and market halls.
Alfred Waterhouse used steel in his later buildings, which in 1880 could be mass produced at low cost. This allowed architects to take buildings to greater heights and it’s still being used in construction today.