At the close of the twelfth century the architects of the Ile-de-France adopted a square form for the body of the tower, and in imitation of Oriental and Rhenish builders, reserved the octagonal plan for the spire, ensuring the solidity of the angles by a variety of ingenious combinations. The great central towers of the Norman churches built in England and Normandy from the thirteenth to the fourteenth century were not always merely belfries, as at Salisbury or Langrune, for instance; in many cases they were lanterns, their functions being to light the centre of the church and to form a magnificent decorative feature at the intersection of transepts, nave, and choir in cruciform structures, such as St. Georges, Bocherville, Coutances, etc. Of all the French provinces Normandy clung most persistently to the lantern tower, and that of St. Ouen at Rouen is one of the most interesting examples. [Illustration: 87. SALISBURY CATHEDRAL. STEEPLE] [Illustration: 88. CHURCH OF LANGRUNE (CALVADOS). STEEPLE] In other provinces, notably Picardy, Champagne, Burgundy, and the Ile-de-France, lantern towers were superseded by timber _flèches_ cased in lead, which rose at the intersection of the roofs of nave and transepts. Among the most remarkable towers of the twelfth century in the Northern provinces we may mention those of Tracy-le-Val (Oise), of the Abbey Church of the Ste. Trinité at Vendôme, and of Bayeux; those of the Abbaye-aux-Hommes at Caen; the old tower of the Cathedral of Chartres, and that of St. Eusèbe at Auxerre. In the thirteenth century the height and decorative richness of these structures had increased to an extraordinary degree. The tower of Senlis (Fig. 86) is a most elegant example of the first years of a century which witnessed the birth of so many marvels of architecture. In Burgundy several remarkable towers were built by the monks of Cluny, who were free from the asceticism introduced by St. Bernard among their brethren of Citeaux. The most notable of their structures are perhaps the towers of the Church of St. Père, near Vézelay, built about 1240. In the South various original developments in Gothic architecture were logically brought about by a judicious use of the materials of the country, such as brick. Most interesting examples of such development are to be found in the tower of the Jacobin Church at Toulouse, which dates from the close of the thirteenth century, and the donjon tower of Albi, the characteristics of which we have already discussed. [Illustration: 89. CHURCH OF THE JACOBINS AT TOULOUSE. TOWER]