stylistic:style_transfer, linguistic:voice_change
Architecture and art

New basilicas were built in the major Roman cities and post-Roman kingdoms from the 4th to the 6th centuries. Byzantine church architecture adopted an alternative model imitating the rectangular plan and the dome of Justinian's Hagia Sophia, the largest single-roofed structure in the Roman world. As the spacious basilicas became less useful with the decline of urban centres in the west, they gave way to smaller churches until the basilica form of architecture revived in the Carolingian Empire. A new standard feature of Carolingian basilicas is the use of a transept: the "arms" of a T-shaped building which are perpendicular to the long nave. In Al-Andalus, the Great Mosque of Córdoba became an extraordinary example of Moorish architecture.

Halls built of timber or stone were the centres of political and social life. Their design often adopted elements of later Roman architecture such as pilasters, columns, and sculptured discs. After the disintegration of the Carolingian Empire, the spread of aristocratic castles indicates a transition from communal fortifications to private defence. Most castles were wooden structures, but the wealthiest lords built stone fortresses. One or more towers (now known as keeps) were their most characteristic features, but castles often developed into multi-functional compounds with drawbridges, fortified courtyards, cisterns or wells, halls, chapels, stables and workshops.

Gold pouring into the tribal leaders from the Roman Empire was regularly remoulded into new artifacts, such as massive necklaces and eagle-shaped fibulae, by local goldsmiths. Their unrealistic style, often influenced by Iranian polychrome and cloisonné metal works, was introduced into Roman territory by the invading peoples. Artisans working for post-Roman elites developed a distinct, abstract design characterised by ribbons and highly-stylised animal motifs. Literary works such as the Old English epic poem Beowulf and the Nordic sagas refer to great royal treasures, but only a few of them survived; they included grave goods from Childeric's tomb at Tournai and the rich Anglo-Saxon burial at Sutton Hoo. Religious art quickly assimilated several elements of secular style, such as strapwork ornamenting and extensive segmentation. Paintings have mostly survived in richly-decorated Gospel Books, including the Book of Kells and the Lindisfarne Gospels —two examples of the Insular art of Ireland and Northumbria.

The Hellenistic tradition of realistic portrayal survived in the Mediterranean. Although the iconoclastic movement restricted Byzantine art, the iconophiles' triumph paved the way for an artistic renewal. The more naturalistic Mediterranean style was an important inspiration for western artists under Charlemagne, who considered the visual arts a powerful instrument of education and propaganda. After a long pause, Carolingian art rediscovered the human figure and Western artists often depicted people in illuminated codices. These were often protected by sumptuous book covers made of gold, pearls, and polished gemstones. Charlemagne's court seems to have been responsible for the acceptance of figurative monumental sculpture in Christian art and, by the end of the period, near-life-sized figures such as the Gero Cross were common in important churches. In England, book illuminators freely enriched their Insular heritage with Carolingian motifs such as sprigs of foliage. In post-Carolingian Germany, manuscripts illustrated with lively pictorial cycles indicate the impact of contemporary Byzantine art on Ottonian artists. In Christian Spain, artists adopted Islamic decorative motifs such as Kufic letters and Moorish arches.