The Kashi Vishwanath temple is situated in Varanasi, Uttar Pradesh.
Once there was a fight between Lord Brahma and Lord Vishnu over supremacy of creation. Lord Shiva appeared in between them as an infinite pillar of fire. Lord Brahma and Lord Vishnu wanted to see the origin and the end of the pillar. So, Lord Brahma took the form of a swan and went up the pillar of fire to see the origin and Lord Vishnu took the form of a boar and went down the pillar of fire to see the end. They could neither find the origin nor the end of that
On the way, Lord Brahma met the Ketki flower who told Him that it was fruitless as there was no origin to the pillar of fire. Lord Brahma requested the Ketki flower to tell a lie along with him and he claimed that he had seen the origin of the pillar of fire, whereas Lord Vishnu accepted the defeat. This enraged Lord Shiva and He cursed Lord Brahma that no one will worship him and He declared Lord Vishnu as the Supreme God. Similarly, the Ketki flower was also cursed that she would never be used in worship of Lord Shiva.
The pillar of fire vanished and thereafter a small portion of it remained at Varanasi, as jyotirlinga called Kashi Vishwanath. A darshan of this jyotirlinga is said to bestow mukti toa a person.