It was not until 1880 that an era of construction based on reliable mild steel began. By that date the quality of steels being produced had become reasonably consistent. The Home Insurance Building, completed in 1885, was the first to use skeleton frame construction, relying on its masonry cladding for stability.

Wrought iron was actually "wrought" (i.e. worked or hammered) into bars and has been used as a construction material for thousands of years. Most metals used for construction purposes are alloys. For example, steel is an alloy with iron and carbon being the primary elements.