For the past five millennia, artists and architects have used mosaics to decorate walls, ceilings, floors, and other surfaces of both interior and exterior spaces. When you think of the word mosaic, you might think of a patchwork pattern, or an image composed of smaller, geometrical shapes. Although mosaics through the ages have taken on a number of forms, it is the basic division of a surface or motif into various "building-block" pieces that give mosaics their distinctive look.
The fragmented look that makes mosaics so unique comes from the many small bits of colored stone, tile, or glass, called tesserae, which are set into plaster or concrete. The word tesserae, in fact, reveals a great deal about the art of mosaics. It comes from the Greek word tessares, meaning "four," and is also related to the Latin word tessellatus, which means "of small square stones." One of the properties of a square is that it can tessellate a surface--that is, this shape can be repeated many times in an arrangement that fills a surface without leaving spaces or overlaps between its pieces. Aside from the example of the square, tessellating patterns can include many combinations and types of shapes, and although some forms of mosaic art do leave slight gaps between pieces, it is their overall arrangement that creates an image reminiscent of a tessellating pattern.
The oldest known mosaics date as far back as the third millennium B.C., and were used to embellish Sumerian architecture. Sumerian wall decorations, an early form of mosaic, contain examples of tessellations. The Greeks and Romans refined this ancient technique to the point where a mosaic artist could reproduce a painting. Roman artists used bits of naturally colored marble as tesserae in their mosaics, and predominantly used them in floor decorations of such spaces as temples and baths.
Early Christian and Byzantine architecture gave rise to a new type of mosaic. Large new churches, called basilicas after a type of ancient Roman building, were being built during this early flowering of Christianity, and the walls of these buildings needed decoration. Christian wall mosaics were made from colored glass tesserae, sometimes backed with gold. The result of this new technique was vast expanses of brilliant, intricate images covering the walls and ceilings of the new basilicas. Long series of biblical scenes were usually the subjects of mosaic decoration.
Mosaic art has endured to this day as a form of decoration in both public and private buildings. You can find it in swimming pools, on furniture, walls, and smaller objects like boxes, photo-mosaic posters, and book covers. Many artisans today are still skilled in mosaic techniques dating from Roman times, and can create new works of art or restore ancient pieces to their former splendor. Indeed, the timeless attraction to the look and feel of mosaics comes in part from the intriguing interplay of many distinct pieces to achieve a complex pattern or picture.