Ujjain was the hub of all activities of Hindu astronomers and astrologers from ancient times, which paved the way for establishment of an observatory in the 17th century. In local phraseology this observatory is called as Jantar Mantar, which is a plagiaristic form of Yantra and Mantra.
Vedh Shala observatory lies to the southeast of the town and consists of four monuments. The first one is a 22 feet high Samrata Yantra, which was used to calculate the time. The Equinoctial days are calculated with the help of the second instrument by name Nadi Walaya Yantra. The position of stars and planets are calculated with the help of the third instrument, Dignasha Yantra. Bhitti Yantra helps to calculate the declination of the sun and the distance of the zenith.
The observatory, which houses a planetarium and a telescope, is a hot spot for stargazers and curious public.