Probably the first modern observatory was built by Arabic astronomers in Shamsiya, near Baghdad and at Mount Qasiyun, near Damascus. In Shamsiya, a building was built for accomodation and work place for astronomers.
The one of the instruments used for observation was armillary sphere. It is a spherical globe with rings and hoops depicting equator, tropics and other celestial circles. It can move on its axis. (Credit:en.wikipedia.org)