What one material was invented and revolutionized the concept of architecture in the Roman Empire?
Roman concrete (also called Opus caementicium) was a material used in construction during the Roman Empire. Roman concrete was based on a hydraulic-setting cement with many material qualities similar to modern Portland cement. By the middle of the first century AD, the material was used frequently as brick-faced concrete, although variations in aggregate allowed different arrangements of materials. Further innovative developments in the material, coined the Roman Concrete Revolution, contributed to structurally complicated forms, such as the Pantheon dome.
