The earliest intact figures are five prophet windows at Augsburg, dating from the late 11th century. The figures, though stiff and formalised, demonstrate considerable proficiency in design, both pictorially and in the functional use of the glass, indicating that their maker was well accustomed to the medium. At Canterbury and Chartres Cathedrals, a number of panels of the 12th century have survived, including, at Canterbury, a figure of Adam digging, and another of his son Seth from a series of Ancestors of Christ. Adam represents a highly naturalistic and lively portrayal, while in the figure of Seth, the robes have been used to great decorative effect, similar to the best stone carving of the period. Many of the magnificent stained glass windows of France, including the famous windows of Chartres, date from the 13th century. Far fewer large windows remain intact from the 12th century. One such is the Crucifixion of Poitiers, a remarkable composition that rises through three stages, the lowest with a quatrefoil depicting the Martyrdom of St Peter, the largest central stage dominated by the crucifixion and the upper stage showing the Ascension of Christ in a mandorla. The figure of the crucified Christ is already showing the Gothic curve. The window is described by George Seddon as being of "unforgettable beauty". During the 12th century, features that were to become typical of Gothic architecture began to appear. It is not uncommon, for example, for a part of building that has been constructed over a lengthy period extending into the 12th century, to have very similar arcading of both semi-circular and pointed shape, or windows that are identical in height and width, but in which the later ones are pointed. This can be seen on the towers of Tournai Cathedral and on the western towers and facade at Ely Cathedral. Other variations that appear to hover between Romanesque and Gothic occur, such as the facade designed by Abbot Suger at the Abbey of Saint-Denis, which retains much that is Romanesque in its appearance, and the Facade of Laon Cathedral, which, despite its Gothic form, has round arches. Abbot Suger's innovative choir of the Abbey of Saint-Denis, 1140–44, led to the adoption of the Gothic style by Paris and its surrounding area, but other parts of France were slower to take it up, and provincial churches continued to be built in the heavy manner and rubble stone of the Romanesque, even when the openings were treated with the fashionable pointed arch.