Jantar Mantar of Jaipur in Rajasthan, a stone observatory, has several instruments that help in calculating time and are useful also for the studies related to celestial objects. In the Rajput era, it was a unique creation. One of the most important "yantras" here is the Ram Yantra. Ram Yantra is an instrument, which is used to measure the local co-ordinates of altitude and azimuth of celestial objects. The main feature of the instrument is that it gives the direct readings.

Structure of Ram Yantra
As the tourists check out the instrument, they will find that it comprises of two circular stone buildings. When seen together it becomes one unit. Though they are constructed at a distance they are complementary to each other. In the centre of the two units there is a fixed perpendicular rod. This particular rod is of the same height as the building.

Besides these there are twelve stone triangles that are fixed to the ground. These stone slabs are divided up from 90 ° to 45 °. The circular wall of Ram Yantra is marked off from 45 to 0 °. These two complementary instruments display the movement of the Sun from the standpoint of the location of the individual on the Earth. Wherever one Ram Yantra has solid portions, the other has open spaces. While one instrument shows the shadow cast by the top of the central post, the other instrument does not register a shadow.

Purpose of Ram Yantra
Ram Yantra is used alternately as the Sun moves across the sky. The base of the central post of Ram Yantra represents the zenith point, and the ring on top of the vertical columns represents the horizon line. These instruments determine the altitude and azimuth of the Sun.

Ram Yantra displays the fullness on the move- Purnamadah-Purnamidam. Fullness on the move is what generates different aspects of physiology. The total intelligence on the move of Ram Yantra means total Natural Law or potential Natural Law becoming livelier and appearing as specific Laws of Nature, which are then expressed as the physiological structures. Both the common basis of all the specific physiological structures, the non-specific ocean of Intelligence, and the specific physiological structures become lively through observing the Ram Yantra.

The use of Ram Yantras can be taken to touch the horizon of unity consciousness -a quiet influence of unfolding the supreme reality, which is manifest and unmanifest (solid and hollow) both at the same time. Viewing of the Ram Yantra in Jantar Manar enlivens the process of creation located in the human physiology where intelligence begins to express itself and assumes different forms.