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.
Sanitation in ancient Rome
The Romans recycled public bath waste water by using it as part of the flow that flushed the latrines. Terra cotta piping was used in the plumbing that carried waste water from homes. The Romans were the first to seal pipes in concrete to resist the high water pressures developed in siphons and elsewhere. Beginning around the 5th century BC, aediles, among their other functions, supervised the sanitary systems. They were also responsible for the efficiency of the drainage and sewage systems, the cleansing of the streets, prevention of foul smells, and general oversight of baths.