Ujjain is one of the seven sacred cities (Sapta Puri) of Hinduism, home to the Mahakaleshwar Jyotirlinga — one of the 12 most sacred Shiva shrines in India. Ujjain holds a unique place in Vedic astronomy: it was the prime meridian of the Surya Siddhanta and ancient Indian calendrical science — the original zero longitude of Hindu astronomy. The Simhastha Kumbh Mela held here every 12 years draws 75 million pilgrims. Every ritual at Mahakaleshwar is timed to Ujjain's actual sunrise.
Astronomically precise Rahu Kaal timings for 25 major Indian cities.