It is said that twenty centuries of human effort are represented by the stones of Tours Cathedral.[156] In the base of its façade towers are remains of the city's III-century walls, which had been constructed in their turn with the big stones stolen from the local Roman temples of 50 B.C. For sixteen centuries Mass has been said on this site. In the southwest tower are vestiges of Gregory of Tours' VI-century church, and in the northwest tower traces of the Romanesque cathedral on which worked the philosopher and theologian, Hildebert de Lavardin, the most popular poet of his age and one of the builders of Le Mans Cathedral before promoted to be Tours' sixty-fourth archbishop (1125-34). In refuting Berengar, a canon of Tours, who taught a confused doctrine concerning the Eucharist, Bishop Hildebert was the first to use the term "transubstantiation" in its theological sense. It is said that the custom of elevating the Host in the Mass resulted from the eucharistic controversies started by Berengar. In 1167 a fire, caused by a quarrel over crusaders' treasure, between Louis VII and Henry II Plantagenet, destroyed the Romanesque cathedral of Tours. Bishop Joscion, who died in 1173, planned to construct a Plantagenet Gothic church, since Touraine was in large part under Angevin control, and to the church he began belongs the graceful _bombé_ vault borne on eight slender branches beneath the northwest tower. In 1191 Richard Coeur-de-Lion came to his city of Tours to receive the crusaders' insignia before his venture to the East. His ransom drained the land of building funds. For that cause or another, the projected work at Tours languished. The actual choir was begun only about 1210, when the city had become a part of the royal domain, and its new master Philippe-Auguste wrote that he held the church of Tours to be one of the chief jewels of his crown, and that whosoever molested it touched his (the king's) person.