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.
Productivity improving technologies
Cement is the binder for concrete, which is one of the most widely used construction materials today because of its low cost, versatility and durability. Portland cement, which was invented 1824-5, is made by calcining limestone and other naturally occurring minerals in a kiln. A great advance was the perfection of rotary cement kilns in the 1890s, the method still being used today. Reinforced concrete, which is suitable for structures, began being used in the early 20th century.