84 Mahadev

Ujjain is the land of origin of creation. Anadikalpeshwar manifested itself in form of Shivaling when the earth did not exist nor were there elements when there was no sun, moon, planets or Nakshatras. Neither were there god,nor demons.
Shiva is believed to be Anadi (the one with no beginning). He is the apex of all the gods in creation. Shiva himself has narrated the importance & significance of 84 Mahadevs in a dialogue with Parvati in the Skanda Puran.