Much more is known about Roman interior decoration, and Roman furniture was based on earlier Greek models. From the beginning of the Christian era the predominant Western style was that derived from ancient Greece by way of Rome. Classical styles were based on mathematically expressed laws of proportion that were applied not only to buildings as a whole but also to much of the interior decoration.

Roman interior decoration is known both from literary sources, such as Pliny’s Natural History and the Histories of Suetonius, and from excavations, such as those that uncovered the remains of the Golden House of Nero soon after 1500 and those at Pompeii and Herculaneum in Italy in the 18th century.

There are many misconceptions about the decoration of the period, most of which date from the 18th century and the classical revival that began soon after 1750. Many excavated bronze objects, including statues, and any bronze that remained above ground, such as the roofing of the Capitol, were melted during medieval times for new work, since bronze was a scarce and expensive metal. This led to the assumption that marble predominated, which is not necessarily true, especially in the case of statuary. Time and exposure to the weather has removed the colour from much of the marble that has survived, but in classical times it was commonly painted and sometimes gilded. Wall paintings at Pompeii and Herculaneum are ample testimony to this. Wall decoration began there about 150 bc, and, by about 80 bc, plastered walls were being made to look like masonry. Such decoration was combined with the true architectural features—e.g., doors and pilasters (flattened columns attached to the wall). The panels are painted variously in yellow, black, magenta, and red, with some imitation marbling indicating an earlier custom of applying marble veneers. Rich colour was also supplied by superbly executed mosaic floors, elegant couches with coloured cushions, and bronze tripods and lamps, such as in the cubiculum of a villa at Boscoreale near Pompeii preserved in the Metropolitan Museum in New York City.

Roman wall painting depicted columns, niches, and open windows with elaborate imaginary views and figures beyond. Painted ruins, such as those in the Villa of Livia, Rome, were the precursors of the 18th- and 19th-century Romantic taste in western Europe.

It has been said that Augustus, who was emperor from 27 bc to ad 14, found Rome of brick and left it of marble, and certainly the interior decoration of imperial Rome expressed the emergence of the city as a world power toward which flowed much of the wealth of the empire. Exotic marbles began to be imported, and brick walls were faced with polished slabs of white and coloured stone. In the more luxurious interiors or for special purposes, obsidian, a natural volcanic glass dark green or purplish-brown in colour, and copper-green malachite were occasionally to be found in the capital. A limited amount of window glass—mostly small, thick, and discoloured panes—was used, for sheet glass was difficult to manufacture. Large translucent crystals of selenite (a kind of gypsum) were sometimes employed to admit light.

Some of the large houses contained a picture gallery, known as the pinacoteca, for the display of easel pictures. These have now virtually disappeared, but mural paintings are fairly common. Pictorial decoration for floors and walls was supplied by mosaics, the picture built up of small fragments (tesserae) of coloured stones, mostly marble, or of small pieces of coloured glass backed by gold foil to increase its reflective power. The subjects are very diverse. Floor-mosaics in dining-rooms were sometimes decorated with simulated fragments of food, as though they had dropped from the table.

Roman furniture was made of stone, wood, or bronze. Villas were largely open to the air, and stone benches and tables were common. Wooden furniture has not survived, but bronze hardware for such furniture is well-known. Buffets with tiers of shelves were used to display silver. Tables were often made of exotic woods and veneers, with ivory, bronze, or silver trim. Tortoiseshell veneers were popular. The dining couches, which replaced chairs, were richly decorated, often with gilded silver or bronze. Chairs followed earlier Greek forms, and while no fixed upholstery was provided, cushions were plentiful.

The art of tapestry came to Rome from Egypt, where the craft was an ancient one. Few Roman textiles have survived, and those have mostly been found in Egypt and were probably made there. Rugs woven on a linen foundation were imported from Egypt, and fabrics, including rugs, were imported from the Near East. The richest carpets came from Pergamos, in Asia Minor, and were the most highly valued. They were probably woven with gold and silver thread. Nothing survives of these rich textiles because they were all burned long ago to extract the metal. Roman walls were hung with tapestries, and pillars were decorated with textiles. Silk was imported from China until the time of Justinian, in the 6th century, when silkworms were clandestinely brought from East Asia and the industry was established in Europe.

The Romans were highly skilled glassworkers. Domestic glass was made in large quantities, both utilitarian and decorative, and factories were established for the purpose. Mirrors, however, were normally made of polished bronze or silver; if glass mirrors existed at all, they must have been very small.

The amount of bronze employed in household equipment of all kinds was vast. Small pieces of furniture, such as stools, were made wholly of bronze, and a few specimens have survived. Saucepans were made in factories, some bearing what appears to be the trademark of a swan. Lighting fixtures were also made in quantity, of prefabricated parts, and they played a large part in the decoration of the interior. By the 1st century ad enormous quantities of silver went into the making of such objects as large and heavy platters displayed on the buffets. Bowls and similar pieces of hollow ware were commonly decorated with repoussé ornament, less often with engraving, which is usually to be found on the backs of bronze hand mirrors. Antique silver commanded a high price.

Statuary in bronze, from Etruscan sources or looted from Greece and the Greek colonies, decorated the more important interiors. The theatre of Scaurus, for instance, housed 3,000 bronze statues. Some Roman statues have been excavated at Pompeii and elsewhere, but most were remelted. Only one Roman bronze statue has remained above ground in Italy since it was made—the equestrian Marcus Aurelius in Rome.

Pottery was not among the luxuries of ancient Rome. Vessels such as storage jars (amphorae), lamps, bricks, pipes, and architectural ornament were made in factories. Pottery for the table was usually of the so-called Samian ware, although it was made in many other places than Samos; this had a red polished surface and, often, molded relief decoration reminiscent of contemporary silver. Tableware, too, was made in factories and often marked with the name of the potter. Pottery vases of fine quality were made in imitation of those of Greece. They include most of the familiar Greek types, especially the krater (with a large round body, large mouth, and small handles), although the form often varies. The decoration is principally of the red-figure type (black with decorations in red) but is usually much more elaborate than on the Greek originals.

Themes of decoration are many, and most come from Greek sources. They became part of the vocabulary of classical ornament that was employed during later classical revivals, such as the Renaissance and the Neoclassical movement of the 18th century. The acanthus leaf is by far the most common, and it was in almost continuous use from the 5th century bc in Greece to the 19th century in the West. The Greek and Byzantine acanthus leaf is inclined to be stiff and formal; the Roman and Renaissance form is much more natural. The vine-leaf and grapes motif is also common, and the palmette occurs especially on painted vases. The ivy, laurel, olive, and honeysuckle (anthemion) are usually to be found as frieze ornament, sometimes in stylized form. Festoons, garlands, and swags of laurel were common decorative elements in relief sculpture. “Cable,” or “twisted rope,” a kind of plaited ornament, was often used for the same purpose. Rosettes—stylized simple roses with equally spaced petals—were widely used. Originally an Assyrian design, they have continued in use to the present. Egglike forms alternating with tongue- or dart-shaped ornaments originally were a carved stone architectural ornament; they were taken over in later times as part of interior plasterwork.

The lion was very popular, especially the mask and paws, and was employed over a long period, as late as the 19th century, as a furniture ornament or as a door knocker or handle. Mythological animal forms included the griffin and the chimera, both of Mesopotamian origin, and the sphinx, from Egypt and Corinthian Greece. The head of the ram, a sacrificial animal, commonly ornamented altars and candelabra. The ox skull and horns occur during Roman times, but not often thereafter. The eagle, representing Jupiter, was the symbolic motif of the Roman legions. The human mask surrounded by foliage was common and is usually derived from the masks employed in the theatre or from the head of Medusa, which was especially used as a shield ornament. Atlantes and caryatids, male and female human figures, respectively, were originally used instead of plain columns on building exteriors but were later employed for a variety of ornamental purposes—for example, as part of the decoration of some Renaissance cabinets of architectural form. Trophies were always popular. Weapons arranged in a pattern were carried in the Roman triumphs and later sculptured on monuments. This classical form of ornament was later extended to other groups of implements: in the 18th century, for instance, rustic trophies were formed by grouping agricultural implements, such as spades, beehives, and rakes, into a decorative pattern, and musical trophies were made of musical instruments for the same purpose.

A common type of decoration surviving especially in Pompeii is the frieze of small putti, or cupids, in a variety of guises and at work at a large number of different tasks. These persisted in popularity until well into the 18th century, when porcelain figures of putti in disguise or in an allegorical pose became common. They were also painted on furniture or as part of wall decoration.

Equally popular, but remaining virtually unknown till the discovery of the Golden House of Nero c. 1500, are the ornamental motifs known as grotesques (because they were found below ground in a “grotto,” a word that strictly means an excavated chamber containing murals). Roman grotesques were fantastic figures, human and animal, that terminated in leafage (usually the acanthus leaf) or in a fishtail, in conjunction with floral and foliate ornament and arabesques. Revived by Raphael about 1517 for the decoration of the loggia of the Vatican, these motifs became widely popular, in many different forms, from the first decade of the 16th century until late in the 18th.