According to eshraag.com website, the Niujie Mosque will every day host worshippers who have registered the day before.
The Niujie Mosque or Beijing Cow Street Mosque is an ancient Muslim place of worship that is thought to be among the oldest and most important mosques in China.
It was first built in 996 during the Liao Dynasty and was reconstructed as well as enlarged under the Kangxi Emperor (1661–1722) of the Qing Dynasty.
The Mosque is located in the Niujie area of Beijing's Xicheng District, the spiritual center for the 10,000 Muslims living in the vicinity.