Northwest China's Xi'an city, known for its history as the capital of a dozen of Chinese dynasties, on Monday started preservation work on a landmark city gate dating back more than 1,000 years.

Local cultural heritage bureau launched the project on the relics of Mingde Gate, the south gate of the city wall built in Tang Dynasty (618 A.D.- 907 A.D.), and unearthed between 1972 and 1973.

The base of Mingde Gate and the wall is 55.5 meters long and 17.5 meters wide. Local cultural heritage bureau plans to build explanatory signs for the relics, use glass covers to protect some parts of it and set up an exhibition hall to show its history and culture.

The city has also set up 30 mu (2 hectares) of preservation area around the relics site.

Xi'an boasts well-preserved ancient city walls used as fortifications for military defense. The most known city walls were built from 1370 to 1378 with a total length of 13.7 kilometers.