A Nine-Dragon Wall Made of Glazed Tile

The wall stands on Heyang Street in the old city, a screen built to face the residence of a Ming prince. A screen of this kind stands across the approach to a gate and closes the view from the street. It was put up between 1392 and 1396 for Zhu Gui, Prince Dai, the thirteenth son of the Ming founder Zhu Yuanzhang, and it is 45.5 metres long, 8 metres high and 2.02 metres thick. The dragons on it have four claws, not five. A prince's house was allowed the four-clawed dragon, the python of the ritual codes, and the difference can be counted along the face: nine dragons in relief, each one short a claw.

The way the wall was moved tells you how it was built. In August 1954 the city needed the road, so the wall was taken down and put back together twenty-eight metres south of its original line, the old pieces refitted in their old order, with grey brick making up the parts that had been lost. That is only possible because the face is a skin of separate fired units set against a brick body, each one shaped and glazed before it went up. A lead glaze fuses to the tile in the kiln, which is why the colour reads as one sheet across more than forty metres rather than as paint.

Datong calls itself the city of dragon walls, and nine of them survive. This is the most famous, and the comparison usually made is with Beijing: the nine-dragon walls of the Forbidden City and of the lake at Beihai are more than three hundred years later, and the Beihai wall is about half the size of this one. What the difference shows is a change in taste as much as in rank, a Ming princely screen of the 1390s against the imperial walls of a later court. This wall was listed as a national key cultural relics protection unit in 2001, in the fifth batch.