Ancient Roman architecture borrowed heavily from Greek architecture, such as the huge columns used in temples, but it soon developed its own distinctive style of domes, arches and vaults. These features hadn’t been used before and can be attributed to the innovative use of concrete by the Romans. They also learnt from the Etruscans to the north with their knowledge of hydraulics and arch construction.
The Romans’ use of arches allowed them to build aqueducts across the empire. Examples include 11 aqueducts in Rome and the almost intact Aqueduct of Segovia on the Iberian Peninsula. Many bridges were constructed using the same principle, such as the Merida Bridge over two forks of the Guadiana River in Spain with its 60 arches. Similarly, the invention of the dome produced innovations in public building. Vaulted ceilings allowed taller, wider public buildings, including basilicas and bath houses. Huge temples were constructed, such as the Pantheon in Rome with its large concrete dome and its open spaces. Over 220 amphitheatres, including the Colosseum, were used for public meetings, displays, and gladiatorial contests. The Romans built many lighthouses too. Many of their buildings and structures still stand.
Private housing and associated structures were also made to last. Most obvious are private baths and latrines as well as water pipes, hypocausts for under floor heating, and double glazing. The Romans built multi-story apartment blocks or “insula.” The residences within these blocks were semi-detached and each one had its own terrace and entrance. Apartments had a similar floor plan, making these buildings cheap and easy to construct. Rooms were basic yet functional. Interior walls were often plastered and painted in colorful patterns such as alternating stripes of red and rainbow. Despite being regarded as unhealthy fire hazards, some of these building still stand, such as in the Roman city of Ostia.
In the early period of Roman civilization, the predominant building material was marble. This was used to construct buildings with thick columns supporting flat architraves, very much in the Greek style. When concrete became the main material, covered with tiles, larger and more imposing buildings were erected, with pillars supporting arches and domes. Concrete allowed colonnade screens of decorative columns to be erected in front of load bearing walls. It also allowed large open spaces within buildings rather than smaller rectangular cells.
Concrete wasn’t invented by the Romans. This honor probably goes to the Mesopotamians, who used it as a minor or supplementary material. But the Romans were the first to use it on a large scale. Their concrete included stones, sand, water and lime mortar, making it stronger than earlier concrete. These ingredients were put into wooden frames and allowed to harden and bond with bricks or stones to make a strong wall. The surface was smoothed and a layer of stucco or tiles of marble or other stone was added. Mosaic patterns made of colored stone became popular in the first and second centuries for both public and private buildings, complementing the murals that already decorated many floors and walls.
The greater use of concrete and the resulting grandeur of Roman public architecture greatly assisted the expansion of the empire. The buildings were not only constructed to perform their intended use but also to impress. They were very durable, many of them withstanding wars and the environment for 2000 years.