<P> The Cistercians acquired a reputation in the difficult task of administering the building sites for abbeys and cathedrals . St Bernard's own brother, Achard, is known to have supervised the construction of many abbeys, such as Himmerod Abbey in the Rhineland . Others were Raoul at Saint - Jouin - de-Marnes, who later became abbot there; Geoffrey d'Aignay, sent to Fountains Abbey in 1133; and Robert, sent to Mellifont Abbey in 1142 . On one occasion the Abbot of La Trinité at Vendôme loaned a monk named John to the Bishop of Le Mans, Hildebert de Lavardin, for the building of a cathedral; after the project was completed, John refused to return to his monastery . </P> <P> The Cistercians "made it a point of honour to recruit the best stonecutters", and as early as 1133, St Bernard was hiring workers to help the monks erect new buildings at Clairvaux . It is from the 12th century Byland Abbey in Yorkshire that the oldest recorded example of architectural tracing is found . Tracings were architectural drawings incised and painted in stone, to a depth of 2--3 mm, showing architectural detail to scale . The first tracing in Byland illustrates a west rose window, while the second depicts the central part of that same window . Later, an illustration from the latter half of the 16th century would show monks working alongside other craftsmen in the construction of Schönau Abbey . </P> <P> Because of the variety found in Cistercian communities, French historian Marcel Aubert concluded that, while there was a Cistercian spirit in architecture, there was never a Cistercian architectural style . </P> <P> The Cistercian order was quite innovative in developing techniques of hydraulic engineering for monasteries established in remote valleys . In Spain, one of the earliest surviving Cistercian houses, the Real Monasterio de Nuestra Senora de Rueda in Aragon, is a good example of such early hydraulic engineering, using a large waterwheel for power and an elaborate water circulation system for central heating . Much of this practicality in Cistercian architecture, and indeed in the construction itself, was made possible by the order's own technological inventiveness . The Cistercians are known to have been skilled metallurgists, and as the historian Alain Erlande - Brandenburg writes: </P>

Which of the following was a characteristic of cistercian architecture and design