Opus africanum

A modern technical term denoting the masonry technique in which walls are constructed by alternating ashlar or orthostatic blocks with fillings of rubble concrete. The technique is mainly found in North Africa, as it was probably emerged from the Phoenician and Punic building tradition.

Opus listatum (also opus vittatum)

A modern technical term denoting the masonry technique in which the facing of a wall consists of alternating layers of brick with layers of small stone blocks. The core of the wall consists of opus caementicium. This technique is also called opus vittatum in modern literature.

Opus quadratum

An ancient technical term to denote a construction technique in which walls are constructed with large squared blocks of stone (ashlars) laid in regular courses, without the use of mortar.

Opus reticulatum

An ancient technical term to denote a construction technique in which the facing of a wall was made by inserting pyramidal stone blocks in an opus caementicium core, hence creating a reticulated, or net, pattern. The quoins (i.e. the outer corners of the walls) were often reinforced with bricks or stone blocks. The technique was mainly used in Central Italy during the (late) 1^st century BC and 1^st century AD, where the blocks were usually made of soft local tuff.

Opus testaceum

A modern technical term denoting the masonry technique in which the facing of a wall consists of regular layers (courses) of flat triangular bricks, embedded in an opus caementicium core.

Opus vittatum

See opus listatum