Astronomical observatories are where astronomers carry out their observation. The shapes of observatories have changed greatly over the years. The earliest were at quiet places set atop city walls or in towers.
To prevent bad viewing, most of the astronomical observatories are located far from city lights high up on mountain tops where the climate is dry and the air is still and clear. Height was important so that the astronomer could have a panoramic, 360° view of the horizon. The Babylonians and the Greeks certainly had rudimentary observatories, but the greatest of the early observatories were those in Islamic North Africa and the Middle East - Baghdad, Cairo and Damascus. The great observatory at Baghdad had a huge 6-m (20-ft) quadrant and 17 m (56-ft) stone sextant. It must have looked very much like the observatory at Jaipur - the only one of this type of observatory to remain relatively intact (below).
Early observations were carried out by the naked eye from the top of monumental architectural structures. The observatory at Jaipur, India, was built by Maharajah Jai Singh in 1726. The monuments include a massive sundial, the Samrat Yantra, and a gnomon inclined at 27° , showing the altitude of Jaipur and the height of Pole Star. There is also a large astronomical sextant and a meridian chamber.
As the great Islamic empires waned and science reawakened in Western Europe, observatories took on a different shape. The oldest observatory still in use is the Observatoire de Paris, founded in1667.
BEIJING OBSERVATORY (above) The Great Observatory set on the walls of the Forbidden City in Beijing, China was constructed with the help of Jesuit Priests from Portugal in 1660 on the site of an older observatory. The instruments included two great armillary spheres, a huge celestial globe, a graduated azimuth horizon ring, and an astronomical quadrant and sextant. The shapes of these instruments were copied from woodcut illustrations in Tycho Brahe's Mechanica of 1598.
Most early telescopes were mounted on astronomical quadrants, and to stabilize the telescope, the quadrant was usually mounted on a wall. These kinds of telescopes are called mural quadrants from the Latin word for "wall", murus. The telescope was hung on a single pivot-point, so that its eyepiece could be moved along the graduated scale of the arc of the quadrant. In this way, astronomers could accurately measure the altitude they were observing.