Roman concrete, also called opus caementicium, was used in construction in ancient Rome. Like its modern equivalent, Roman concrete was based on a hydraulic-setting cement added to an aggregate.
The Pantheon in Rome is an example of Roman concrete construction.
Caesarea harbour: an example of underwater Roman concrete technology on a large scale
The so-called "Temple of Mercury" in Baiae, a Roman frigidarium pool of a bathhouse built in the 1st century BC containing the oldest surviving concrete dome, and largest one before the Pantheon.
Example of opus caementicium on a tomb on the ancient Appian Way in Rome. The original covering has been removed.
Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water, and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined.
A single concrete block, as used for construction
Exterior of the Roman Pantheon, finished 128 AD, the largest unreinforced concrete dome in the world.
Interior of the Pantheon dome, seen from beneath. The concrete for the coffered dome was laid on moulds, mounted on temporary scaffolding.
Opus caementicium exposed in a characteristic Roman arch. In contrast to modern concrete structures, the concrete used in Roman buildings was usually covered with brick or stone.
