In the decorative sphere, Roman art gave pride of place to the mosaic, which was used for ceilings, walls, and floors in particular. This technique involves creating designs based on small stone cubes in different colours, known as tesserae; less commonly, the material used could be brick or a paste of glass. The tesserae were arranged on a fresh mortar base which solidified when dry.
This technique inherited from the Greeks has above all a practical function. Surfaces covered in this way are sturdy and can be washed more easily. Depending on the nature of the rooms to be decorated, and the budget and taste of the person commissioning the work, the mosaic could be a simple, plain paving, or form a carpet of complex representations. Subjects were drawn from mythology, as well as everyday scenes.
Several types of mosaic can be differentiated: the opus vermiculatum consisted of the most faithful imitation of painting effects and their nuances that could be achieved; in this case the tesserae were extremely delicate (sides measuring just a few millimetres). In the case of the opus tesselatum the cubes were slightly bigger (8-10 mm sides) but the speed of execution made it possible to cover large areas. Different trends can be distinguished: the workshops of Rome and Ostia which were at their peak in the 2nd century under Trajan and Hadrian, favoured black figures on a white background, and the graphic effects created by this contrast.
The African mosaic workshops (which testify to the mosaic’s success throughout the Empire) preferred polychrome designs with a marked taste for hunting and amphitheatre scenes. In the Eastern part of the Empire, mythological scenes rendered in a style closer to painting were more popular.
