Roman mosaics were a common feature of private homes and public buildings across the empire from Africa to Antioch. Not only are mosaics beautiful works of art in themselves but they are also an invaluable record of such everyday items as clothes, food, tools, weapons, flora, and fauna. They also reveal much about Roman activities like gladiator contests, sports, agriculture, hunting and sometimes they even capture the Romans themselves in detailed and realistic portraits. Mosaics, otherwise known as opus tessellatum, were made with small black, white, and colored squares typically measuring between 0.5 and 1.5 cm but fine details were often rendered using even smaller pieces as little as 1mm in size. These squares (tesserae or tessellae) were cut from materials such as marble, tile, glass, smalto (glass paste), pottery, stone, and even shells. A base was first prepared with fresh mortar and the tesserae positioned as close together as possible with any gaps then filled with liquid mortar in a process known as grouting. The whole was then cleaned and polished.