China: Beijing's Niujie Mosque (built: 996)
From Cambridge scholar T. J. Winter:
In China, mosques look very like traditional Chinese garden-temples, except that there is a prayer hall without idols, and the calligraphy is Qur'anic. In some of the most beautiful, you will find, as you enter, the following words in Chinese inscribed on a tablet:
Sages have one mind and the same truth. In all parts of the world, sages arise who possess this uniformity of mind and truth. Muhammad, the Great Sage of the West, lived in Arabia long after Confucius, the Sage of China. Though separated by ages and countries, they had the same mind and Truth.