Nobody actually knows when the labyrinth was constructed, because no surviving documents record that information, although various writers have published dates of 1200, 1220 and 1235, even as late as 1240, all given as if they were provable installation dates. The architectural detective work of John James (James, 1990) suggests that the labyrinth must have been laid early in the first decade of the 13th century (c.1201-1205 is a commonly quoted figure), as its position is so integral to the geometric layout of the cathedral, but this argument has a hint of circularity. Craig Wright (Wright, 2001) places its construction around 1215-1221, when the construction of the nave was essentially complete and the masons moved on to finish other parts of the cathedral structure. As the masons would surely not have invested considerable time and expense in installing the labyrinth while there was still the possibility of damage by falling masonry, from work on the roof above, this would seem a sensible dating. Besides, until the construction scaffolding surrounding the pillars in the nave was removed, it would have been very difficult to install the labyrinth, the outer circuits of which run very close to the base of the pillars on either side.