Nanjing has launched the annual maintenance of its City Wall, the key historical and cultural remains of Ming Dynasty (1368-1644), before the arrival of the rainy season.

The City Wall built originally in 1366 is the longest, largest and best-preserved ancient city wall in the world.

At the Jiefang Gate section of the wall, maintenance workers cleaned up small trees and weeds. They also filled the wall cracks with a special material that does not harm the masonry while preventing rainwater from seeping in.

According to the Nanjing City Wall Protection Management Center, roots of grass and trees will lead to crack expansion or fracture of the wall bricks. Secretions and pulp of some plants can also erode the structure. As a result, it’s necessary to have the maintenance work in every spring and autumn.

In addition to the facelift, the city has also made efforts to collect and reuse the old bricks for maintenance.

Nanjing has also invested 30 million yuan to build a monitoring and early warning platform that covers all aspects of the structure, such as hydrological and geological changes, bricks expansion and cracks. The various instruments on the wall can detect movement at millimeter level, upload the data to the center in real time to help ensure effective monitoring and response.

Photo/ Zhang Yun, Zhao Yaling

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