The earliest known mosaics were excavated in what was once Uruk, Mesopotamia, and dated to 4,000 B.C. They were made by pressing cones of clay point-first into wet plaster. By the 8th century B.C., decorative pavements were created using colored pebbles. Initially these were unworked, but later the pebbles were split to give a flatter surface. By the 4th century B.C., the Greeks had raised pebble mosaics to a fine art.
The Romans adopted mosaic making from the Greeks, and many ancient Roman mosaics were made by Greek artists. Colored stones were largely supplanted by tesserae made from glazed tile. For wall mosaics, glass tesserae came into use, offering brilliant colors. With smaller tesserae, some only fractions of an inch in size, more detailed works could be created. Mosaics came to rival paintings in color and detail.
Geometric patterns lend themselves well to mosaics and were very popular with the Romans, both as framing for a pictorial image or as designs in their own right. Roman mosaics often depicted Roman gods and goddesses or other mythological figures and scenes. Other common themes were figures and events from the everyday life of a wealthy Roman, such as gladiators and gladiatorial contests or hunting scenes.