Concrete—cheap, durable, and versatile—was one of
Rome's greatest contributions to architecture. Here, Tony
Rook, a building materials specialist before he studied
archeology, makes concrete the way the Romans might have.
An ancient recipe for concrete comes down to us from the Roman
architect Vitruvius. The recipe calls for quicklime mixed with
water, which turns into a fine powder. As more water is added,
the powder becomes a putty that holds together the sand and
small rocks that are added. The Romans added crushed tile or
volcanic ash to waterproof the concrete, making it perfect for
structures such as aqueducts and baths.