mosaic

A Roman mosaic of a charioteer, at Trier. The Romans frequently used mosaic in their baths and villas.

Ancient floor mosaic at Masada, on the western shore of the Dead Sea in Israel. The fortified palace was built by Herod the Great in the 1st century BC. Excavation of the site was directed by Israeli archaeologist Yigael Yadin.

Detail of the Deesis Mosaic in the museum of Hagia Sophia in Istanbul, Turkey. Dating from the early 14th century, it depicts the figure of Christ (shown here) flanked by the Virgin Mary and John the Baptist.

A detail from a mosaic of fish in the sea from the basilica of Aquileia, Italy, dating from the 4th century AD. Wealthier Christian churches were the leaders in the creation of a late Roman art combining pagan motifs with Christian ones. In this mosaic, behind the traditional naturalistic content of a Nilotic scene, there is the Christian symbolism of fish and a fisherman. The basilica of Aquileia played a key role in the early conversion of a large region of Central Europe.

A fine example of Roman mosaic work that was found in a house in Pompeii, Italy. Mosaic was an art form at which the Romans truly excelled. This example has come to be known as Cave canem! (‘Beware of the Dog!’), although the animal in question does not look particularly ferocious and is on a strong lead.

The famous ‘Alexander mosaic’ at Pompeii, Italy, dating from the early 1st century BC and depicting the Battle of Issus between Alexander the Great and the Persian King Darius III. Its historical subject and its pictorial quality suggest not only a strong Hellenic influence, but also that it was copied from a painting executed by Philoxenos in about 300 BC, which was well known in the ancient world but has since been lost.

Detail of a 12th-century mosaic, showing St Gregory, in the Church of San Clemente, Rome, Italy. The church was originally built prior to 385, and today consists of two churches, a lower and an upper. The upper church was built during the 12th century, and the mosaic of the Triumph of the Cross in its apse dates to that period.

One of the mosaics for which Ravenna is well known, a depiction of the Roman port of Classis, showing the castle battlements and ships in the harbour, 6th century AD (San Apollinare Nuovo, Ravenna). Ravenna, occupied by the Byzantine general Belisarius in 540, became the administrative centre of government in Italy during the Byzantine era. The mosaics at San Apollinare Nuovo are among the finest examples of the fusion of classical and Byzantine styles that typify 5th- and 6th-century art in Italy.

Design or picture, usually for a floor or wall, produced by setting small pieces (tesserae) of marble, glass, or other materials in a cement ground. The ancient Greeks were the first to use large-scale mosaic (in the Macedonian royal palace at Pella, for example). Mosaic was commonly used by the Romans for their baths and villas (a well-known example being at Hadrian's Villa in Tivoli) and reached its highest development in the early Byzantine period (for example, in the church of San Vitale, Ravenna).

Earliest forms

Mosaic was used in Mesopotamia and ancient Egypt for ornament on a small scale. Jewellery and movable objects, such as the Standard of Ur (British Museum), are examples.

Roman

Mosaic pavement, which seems to have originated with the ancient Greeks, reached its highest development among the Romans. Roman mosaic varies from the formal pattern to elaborately pictorial effect. Famous examples are the doves of Pliny at Hadrian's villa, Tivoli, represented with great delicacy of colouring, and the mosaic copy from Pompeii of the battle between Alexander and Darius, after the painter Philoxenos. In Britain, mosaic floors often survive on the sites of Roman villas.

Byzantine

In the Byzantine period, mosaic in the form of coloured and gilded glass was impressively used for mural decoration on a large scale. The richness of gold leaf, calculated irregularities of surface, and the juxtaposition of different colours are combined with a great simplicity of form. Mosaic remained the dominant form of mural ‘painting’ until the rise of fresco in Italy.

In Rome the early Christian mosaics in the churches of Sta Costanza (4th century) and Sta Maria Maggiore (4th–5th centuries) are the first great examples of religious composition. In Ravenna there are the famous masterpieces of the church of S Vitale (6th century) representing the Emperor Justinian, the Empress Theodora, and their attendants. Other masterpieces at Ravenna are Sant' Apollinare Nuovo and the tomb of Galla Placidia. In the cathedral of Torcello, near Venice, there are mosaics dating from the 12th century.

Other important examples are the mosaics found in Istanbul (formerly Constantinople) in the cathedral of Sta Sophia (now Hagia Sophia; 6th century), and the church of Kariye Camii (13th century). In Greece there are mosaics in the church of S Demetrios, Salonika (7th century); in the church of Daphni (between Athens and Eleusis; 11th century); and, near Athens, at Hosias Lukas (11th century). In Kiev in Russia there are important mosaics dating from the 11th century.

Byzantine artists worked in many centres, not only in Greece and Italy, but also in Palermo and Monreale in Sicily (which saw a great flowering of mosaic painting in the 12th century), Cologne, Cordova, Jerusalem, and Damascus.

Later mosaics

In modern times the art of mosaic seems to have been well preserved only in Venice. There both Byzantine tradition and later developments are represented in St Mark's Cathedral, which has a sequence of work from the 12th to 18th centuries, with later examples designed by Titian and Tiepolo.

More recent attempts to revive pictorial mosaic have not been very successful. In England during the 19th century the Arts and Crafts Movement and the Gothic Revival led to some small-scale mosaics in churches, and W B Richmond produced work in St Paul's Cathedral.

Among 20th-century figurative mosaics, there are those of the Swedish artist Einar Forseth for the City Hall, Stockholm, and of English artist Boris Anrep for Westminster Cathedral, London, and for the floor of the entrance hall of the National Gallery, London.

Mosaic

Browser program used for searching the World Wide Web. It was distributed free of charge on the Internet as NCSA Mosaic, and made a significant contribution to the huge growth in the Internet's popularity.

Mosaic was developed at the National Center for Supercomputing Applications (NCSA) at the University of Illinois in 1993, and the team behind it went on to create Netscape Navigator, which quickly became a killer application for browsing the Web. The Spyglass version of Mosaic was used as the basis for Microsoft's Internet Explorer browser. The NCSA stopped further development of Mosaic in 1997.