Ujjain is one of the holiest cities in India. According to Indian astrology, zero degrees begins in Ujjain. According to the Mahabharata's Aranya-parva, Ujjain is one of the seven sacred moksa-puris or sapta-puris. The others are Ayodhya, Mathura, Haridwar, Kashi (Varanasi), Kanchipuram, and Dwarka. It is said that Siva killed the demon Tripura at Ujjain.