Escalada. Some 19th-century liturgists supposed that these early altar screens might have represented the origins of the medieval rood screens; but this view is rejected by most current scholars, who emphasize that these screens were intended to separate the altar from the ritual choir, whereas the medieval rood screen separated the ritual choir from the lay congregation. Great Rood The Great Rood or Rood cross itself long preceded the development of screen lofts, originally being either just hung from the chancel arch or also supported by a plain beam across the arch, and high up, typically at the level of the capitals of the columns (if there are any), or near the point where the arch begins to lean inwards. Numerous near life-size crucifixes survive from the Romanesque period or earlier, with the Gero Cross in Cologne Cathedral (965–970) and the Volto Santo of Lucca the best known. Such crosses are commonly referred to in German as Triumphkreuz or triumphal cross. The prototype may have been one known to have been set up in Charlemagne's Palatine Chapel at Aachen, apparently in gold foil worked over a wooden core in the manner of the Golden Madonna of Essen. The original location and support for the surviving figures is often not clear many are now hung on walls- but a number of northern European churches, especially in Germany and Scandinavia, preserve the original setting in full – they are known as a "Triumphkreutz" in German, from the "triumphal arch" (chancel arch in later terms) of Early Christian architecture. As in later examples a Virgin and Saint John often flanked the cross, and cherubim and other figures are sometimes seen. Parochial rood screens For most of the medieval period, there would have been no fixed screen or barrier separating the congregational space from the altar space in parish churches in the Latin West; although as noted above, a curtain might be drawn across the altar at specific points in the Mass. Following the exposition of the doctrine of transubstantiation at the fourth Lateran Council of 1215, clergy were required to ensure that the reserved sacrament was to be kept protected from irreverent access or abuse; and accordingly some form of permanent screen came to be seen as essential, as the parish nave was commonly kept open and used for a wide range of secular purposes. Hence the origin of the chancel screen was