Opus quadratum is an ancient Roman construction technique, in which squared blocks of stone of the same height were set in parallel courses, often without the use of mortar

Mortar (masonry)

Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar becomes hard when it sets, resulting in a rigid aggregate structure. Modern mortars are typically made from a mixture of sand, a binder...

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Technique

This technique was used by the Romans from about the 6th century BC and over time, the precision and accuracy of the block cutting improved. The technique continued to be used throughout the age of the Roman Empire

Roman Empire

The Roman Empire was the post-Republican period of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean....

, even after the introduction of mortar, and was often used in addition to other techniques. The type of stone, the size of the blocks, and the way the blocks were put together can all be used to help archeologists date structures that display the technique.

Etruscan way

In early usage (often called the "Etruscan way"), the joints between the blocks introduce discontinuities, making the blocks uneven. Examples of such construction can be found in reservoirs, basements, terrace walls, and temple podiums in Etruscan

Etruscan civilization

Etruscan civilization is the modern English name given to a civilization of ancient Italy in the area corresponding roughly to Tuscany. The ancient Romans called its creators the Tusci or Etrusci...

 cities and Rome

Rome

Rome is the capital of Italy and the country's largest and most populated city and comune, with over 2.7 million residents in . The city is located in the central-western portion of the Italian Peninsula, on the Tiber River within the Lazio region of Italy.Rome's history spans two and a half...

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Greek way

Subsequently (the "Greek way"), the blocks would be placed in one of two rotations. "Stretchers" would be placed so the longer side was on the face of the wall, and "headers" would be placed so the shorter side was on the face of the wall, and would thus extend further back into the wall thickness. Various patterns could be produced by changing how the blocks were placed, and it was common to strengthen the wall by ensuring that the joints between blocks were centered over the blocks in the row below.

Roman concrete

With the introduction of Roman concrete

Roman concrete

Roman concrete was a material used in construction during the late Roman Republic through the whole history of the Roman Empire. Roman concrete was based on a hydraulic-setting cement with many material qualities similar to modern Portland cement...

, continuous outer walls were often constructed, with some blocks laid as headers in order to attach to the inner wall. Tile or marble can be found cemented to such walls, but this was less common for those structures that were particularly load-bearing, such as arches and pillars used for bridges and aqueducts.

See also

• Roman technology
  Roman technology
  Roman technology is the engineering practice which supported Roman civilization and made the expansion of Roman commerce and Roman military possible over nearly a thousand years....
  
  
• Roman architecture
  Roman architecture
  Ancient Roman architecture adopted certain aspects of Ancient Greek architecture, creating a new architectural style. The Romans were indebted to their Etruscan neighbors and forefathers who supplied them with a wealth of knowledge essential for future architectural solutions, such as hydraulics...
  
  
• Roman bridges