The Id Kah Mosque is a mosque  located in Kashgar

Id-Kah-Mosque

, Xinjiang, in the western People’s Republic of China. It is the largest mosque in China and twelfth largest mosque in the world . Every Friday, it houses nearly 10,000 worshippers and may accommodate up to 20,000. The mosque  was built by Saqsiz Mirza in ca. 1442 (although it incorporated older structures dating back to 996) and covers 16,800 square meters.

source : http://thewondrous.com