What did the Romans build?

Spring is the time of heavy building activity - this also applies to Carnuntum (a good insight into this can be found in the latest episode of Moe's Roman Travels). We took this as an opportunity for our new mini-series: The building industry of antiquity. With a strong focus on Carnuntum in Roman times, we always shed light on other aspects of this exciting topic and start like a real house: with the construction materials.

From today's perspective, the building materials used by the Romans look amazingly modern. All of the building materials that are important today, such as clay, wood, stone, brick and lime mortar, were known to the Romans. Steel and glass were also known to the Romans, but steel was mainly used for the manufacture of weapons (steel as a building material has only been in use for around 100 years), glass was used much more sparingly than in today's building industry (mainly for windows).

The Romans were also able to use a technique similar to today's concrete, the so-called casting mortar ("opus caementitium"), for their buildings. Among other things, it was used in the construction of the Pantheon, the Colosseum and various water pipes. In general, the materials were used accordingly in order to achieve the most economical construction possible. As already mentioned, glass was used for windows, the metals iron and bronze in particular were used accordingly.

Cost efficiency as the driving force

The Romans used both air-dried clay bricks and fired bricks. In the first century AD, fired bricks became increasingly important in architecture in Rome compared to air-dried bricks. The dimensions of the bricks were uniform and, depending on the intended use, a multiple or a part was used, which of course simplified many things in everyday construction and shows the rationale in Roman construction technology.

In Carnuntum, there were no fired bricks as building material for walls. They were only used for special components of the heating system (such as hypkausten pillars), suspension plates, channel bases and, above all, for roofing. Why was that when standardized bricks significantly reduce the workload? The simple answer: transportation costs. The stone material required for the walls could be obtained in Carnuntum from the surrounding area, which is of course much cheaper than having to bring standardized bricks from a greater distance.

Most of the rocks from the Hundsheimer Berg, but also rocks from the Leithagebirge, were used here. Hundsheimer Berg is characterized by a variety of rocks such as granite, lime, dolomite and sandstones, all of which are suitable for construction. The decision to build with these materials was therefore primarily a question of cost. Due to their structure, the rocks of the Hundsheimer Berg are not particularly suitable for sculpting work, which is why the marble, which is reserved for special applications, had to be brought in over long distances.

Part 2: Architects in antiquity

Part 3: House extension in antiquity

Sources and further reading:

Vitruvius: Ten Books on Architecture, Reclam.

J.-P. Adam: Roman Building. Materials and Techniques. (1994)

N. Mayr: On the petrology and selected technological properties of the inscription panels of the Roman temple district on the Pfaffenberg near Carnuntum. (Unprinted diploma thesis TU Wien 2003).