Besides the Chinese astronomical clock of Su Song in 1088 mentioned above, contemporary Muslim astronomers also constructed a variety of highly accurate astronomical clocks for use in their mosques and observatories, such as the water-powered astronomical clock by Al-Jazari in 1206, and the astrolabic clock by Ibn al-Shatir in the early 14th century. The most sophisticated timekeeping astrolabes were the geared astrolabe mechanisms designed by Abū Rayhān Bīrūnī in the 11th century and by Muhammad ibn Abi Bakr in the 13th century. These devices functioned as timekeeping devices and also as calendars.