In his book Making the Modern World, Vaclav Smil argues that the most important man-made material is concrete, both in terms of the amount we produce each year and the total mass we’ve laid down. Concrete is the foundation (literally) for the massive expansion of urban areas of the past several decades, which has been a big factor in cutting the rate of extreme poverty in half since 1990. In 1950, the world made roughly as much steel as cement (a key ingredient in concrete); by 2010, steel production had grown by a factor of 8, but cement had gone up by a factor of 25.
This animated GIF shows the dramatic transformation of Shanghai since 1987. Most of what you’re seeing in that picture is concrete, steel, and glass:
A staggering statistic: