wars conducted by Trajan in what is modern day Romania. It is the foremost example of Roman historical relief and one of the great artistic treasures of the ancient world. This unprecedented achievement, over 650 foot of spiraling length, presents not just realistically rendered individuals (over 2,500 of them), but landscapes, animals, ships, and other elements in a continuous visual history – in effect an ancient precursor of a documentary movie. It survived destruction when it was adapted as a base for Christian sculpture. During the Christian era after 300 AD, the decoration of door panels and sarcophagi continued but full-sized sculpture died out and did not appear to be an important element in early churches. Decorative arts Pottery and terracottas The Romans inherited a tradition of art in a wide range of the so-called "minor arts" or decorative art. Most of these flourished most impressively at the luxury level, but large numbers of terracotta figurines, both religious and secular, continued to be produced cheaply, as well as some larger Campana reliefs in terracotta. Roman art did not use vase-painting in the way of the ancient Greeks, but vessels in Ancient Roman pottery were often stylishly decorated in moulded relief. Producers of the millions of small oil lamps sold seem to have relied on attractive decoration to beat competitors and every subject of Roman art except landscape and portraiture is found on them in miniature. Glass Luxury arts included fancy Roman glass in a great range of techniques, many smaller types of which were probably affordable to a good proportion of the Roman public. This was certainly not the case for the most extravagant types of glass, such as the cage cups or diatreta, of which the Lycurgus Cup in the British Museum is a near-unique figurative example in glass that changes colour when seen with light passing through it. The Augustan Portland Vase is the masterpiece of Roman cameo glass, and imitated the style of the large engraved gems (Blacas Cameo, Gemma Augustea, Great Cameo of France) and other hardstone carvings that were also most popular around this time. Mosaic Roman mosaic was a minor art, though often on a very large scale, until the very end of the period, when late-4th-century Christians began to use it for large religious images on walls in their new large churches; in earlier Roman art mosaic was mainly used for floors, curved