Ram Yantra, as it represents by its name, is an instrument, which is very helpful to the astronomers to find out the zenith distance and the altitude of the sun. The beauty of the instrument is, that it gives us direct readings. Basically the instrument consists of two circular stone building. If we unite them together, it becomes one instrument. This way one is complimentary to the other. They are constructed at a reasonable distance. In the center of the instrument a perpendicular rod is fixed, which is of the same height of the building itself.
Twelve stone triangles are fixed above the ground. These triangular stone slabs are graduated from 90 degree to 45 degree, while 45 to 0 degree the graduations are on the circular wall. This is an instrument by which we come to know the movement of stars.
The Ram Yantra consists of a pair of cylindrical structures, open to the sky, each with a pillar or pole at the center. The pillar/post and walls are of equal height, which is also equal to the radius of the structure. The floor and interior surface of the walls are inscribed with scales indicating angles of altitude and azimuth. Ram Yantras were constructed at the Jaipur and Delhi observatories only.