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When the Shrine of the Magi was moved into the centre chapel in 1322, the ambulatory was opened to pilgrims. In order to close-off the chapels, waist-high stone tracery balustrades topped by iron grating were erected at the entry to each chapel. Iron gates to the left and right offered a means of entry. Some of the stone tracery is quite complex in its design, which is very different from the high Gothic motifs in the Cathedral choir that date from the late thirteenth century.