understood. Architecture The architecture of cathedrals, basilicas and abbey churches is characterised by the buildings' large scale and follows one of several branching traditions of form, function and style that all ultimately derive from the Early Christian architectural traditions established in the Constantinian period. Cathedrals in particular, as well as many abbey churches and basilicas, have certain complex structural forms that are found less often in parish churches. They also tend to display a higher level of contemporary architectural style and the work of accomplished craftsmen, and occupy a status both ecclesiastical and social that an ordinary parish church does not have. Such a cathedral or great church is generally one of the finest buildings within its region and is a focus of local pride. Many cathedrals and basilicas, and a number of abbey churches are among the world's most renowned works of architecture. These include St. Peter's Basilica, Notre Dame de Paris, Cologne Cathedral, Salisbury Cathedral, Prague Cathedral, Lincoln Cathedral, the Basilica of St Denis, the Basilica of Santa Maria Maggiore, the Basilica of San Vitale, St Mark's Basilica, Westminster Abbey, Saint Basil's Cathedral, Washington National Cathedral, Basilica of the National Shrine of the Immaculate Conception, Cathedral Basilica of Saint Louis, Gaudí's incomplete Sagrada Familia and the ancient church of Hagia Sophia, now a museum. Hagia Sophia has been described as architectural and cultural icon of Byzantine and Eastern Orthodox civilization. The earliest large churches date from Late Antiquity. As Christianity and the construction of churches and cathedrals spread throughout the world, their manner of building was dependent upon local materials and local techniques. Different styles of architecture developed and their fashion spread, carried by the establishment of monastic orders, by the posting of bishops from one region to another and by the travelling of master stonemasons who served as architects. The styles of the great church buildings are successively known as Early Christian, Byzantine, Romanesque, Gothic, Renaissance, Baroque, various Revival styles of the late 18th to early 20th centuries and Modern. Overlaid on each of the academic styles are the regional characteristics. Some of these characteristics are so typical of a particular country or region that they appear, regardless of style, in the architecture of churches designed many centuries apart. Art Christian art is sacred art which uses themes and imagery from Christianity. Most Christian groups use or have used art to some extent, although some have had