From Under the Heel of the Dragon: Islam, Racism, Crime, and the Uighur in China, by Blaine Kaltman (Ohio U. Press, 2007), pp. 49-50:
Most mosques throughout China’s northwest, and almost all mosques in Xinjiang, are constructed in a traditional Afghani or Arabian style. From an architectural standpoint, Hui mosques in Yunnan and the Great Mosque in Xi’an, where Hui constitute a large portion of the population, could be mistaken for Buddhist or Taoist temples, as could the Niu Jie Mosque in Beijing. Uighur in Urumqi are proud of the way their mosques look, that is, they feel their mosques look Islamic in comparison to Hui mosques built in the style of traditional Chinese temples….
The Niu Jie Mosque is Beijing’s most famous mosque and the one most frequented by the city’s Muslim population. The Niu Jie Mosque is built in the Chinese style. There are no domes or minarets. The roofs slope up at the eaves in the traditional style of the Ming dynasty. Originally built in the ninth century, the mosque’s current architecture is a reflection of enlargements and refurbishments made throughout the Yuan, Ming, and Qing dynasties. There are a number of relics and artifacts inside, many of which are Han and have no relation to Islam. According to one of the mosque’s groundskeepers, an older Han woman, the mosque was completely renovated in 1979.