Kashi is among the holiest of holy spots for visit by the Hindus, and it is the belief that a visit to Kashi Vishwanath during one's lifetime will lead to the liberation and moksha of the soul from the body, and it is therefore that religious minded hindus in India, try to make at least one visit to this place in their lifetime !.
In fact Lord Shiva himself has announced this place to be his Royal residence. Since Lord Shiva's wife's mother felt shame at her son-in-law having no proper place to live, so as to please Parvathi Devi, Lord Shiva asked Nikumbha to provide him with a dwelling place at Kashi.
And it was specifically on the request of Nikumbha that a brahmin named Aunikumbha made Divodas construct a temple for the Lord at this place, and out of extreme pleasure Lord Shiva went on to grant boons to all of his devotees, but Divodas was left out and not not blessed with a son, which lead to him being angered, and in a fit of rage he went on to demolished the structure that he had constructed..In retaliation, Nikubha set a curse on the entire area that it would have no people inhabiting it, and when eventually the place was not having a single soul there.
Lord Shiva again took up his residence out there permanently. And thereafter Lord Shiva along with his consort Parvathi Devi once again started blessing his devotees with wonderful boons. In fact, Parvathi Mata was so pleased that she offered food (annam) to all and sundry and is therefore worshipped as Annapoorani ( giver of food to all ) .