Ancient Roman architecture
Although concrete had been used on a minor scale in Mesopotamia, Roman architects perfected Roman concrete and used it in buildings where it could stand on its own and support a great deal of weight. The first use of concrete by the Romans was in the town of Cosa sometime after 273 BC. Ancient Roman concrete was a mixture of lime mortar, aggregate, pozzolana, water, and stones, and was stronger than previously-used concretes. The ancient builders placed these ingredients in wooden frames where they hardened and bonded to a facing of stones or (more frequently) bricks. The aggregates used were often much larger than in modern concrete, amounting to rubble.
Legacy of the Roman Empire
Some of the more famous examples are the Roman aqueducts (some of which are still in use today), Roman roads, water powered milling machines, thermal heating systems (as employed in Roman baths, and also used in palaces and wealthy homes) sewage and pipe systems and the invention and widespread use of concrete.