Ujjain one of seven sacred places for Hindus.The place boasts of being an important place during reign of King Ashoka for Buddhism and believe me it gives you a feeling that you stand a bit close to god.
SHIVA in all his splendour reigns eternal in this place.
Talking straight let’s start with the most famous of temples in Ujjain - THE MAHAKALESHWARA, one of the 12 jyotirlingas considered to be most sacred places of hindu worship. If you visit this temple, Don’t miss the Bhasma Aarti, it’s a life time experience and after this famous temple you can go about as many temples as you want - Onkareshwara (the famous boat ride), Bade Ganeshji ka Mandir, Kaal bhairav temple, Harsiddhi temple (check out God of death at its peak power with wine disappearing when touched with lips of Mahakaal idol), Gola temple, Navgraha temple (temple devoted to nine planets considered sacred in Hindu religion), Mangalnath, Gopal temple, Siddhavata, Chintaman Ganesh and many more ....absolutely uncountable.You can travel for a month and still find a temple you haven’t visited.
One advice if you wish to travel to these places have a bus, taxi, auto rickshaw hired for a day.By absolutely no means you can go from one place to other searching for vehicle every time.
Hotels : Ranges from cheap to high class.
Food : Purely vegetarian and variety from plain home cooked to spicy snacks at very very cheap prices.
In one line one can explain Ujjain as a peaceful, holy place, an absolute must visit for all religious people looking for life time experience.