Jantar Mantar Delhi – Ancient Astronomical Observatory

Jantar Mantar in Delhi is a remarkable 18th-century astronomical observatory built by Maharaja Jai Singh II of Jaipur in 1724. It is one of five such observatories built by Jai Singh across India — the others being in Jaipur, Ujjain, Mathura, and Varanasi.

The observatory contains 13 architectural astronomical instruments, all built in masonry, that were used to measure time, track celestial bodies, and predict eclipses with remarkable accuracy for their era.

Maharaja Jai Singh II was a passionate astronomer who was dissatisfied with the accuracy of existing brass astronomical instruments. He commissioned a set of massive masonry instruments that could take more precise measurements — and the result was the Jantar Mantar observatories.

Samrat Yantra (Supreme Instrument) – A giant sundial that tells time to an accuracy of half a second

Misra Yantra – A composite instrument used to find the shortest and longest days of the year

Ram Yantra – Two large cylindrical structures used to measure altitudes and azimuths

Jayaprakash Yantra – Two hemispherical bowls used to verify readings of other instruments