Kashi was home to several historic Shiva temples. The Chatur Mukheshwar Temple is one among them. Kashi Khand mentions the significance of this Temple.
Goddess Parvati humbly asked Lord Shiva to explain the many Teerths (Sacred Ponds) and Shiv Lings in the Holy City of Kashi. Lord Shiva obliged. Devotees can discover the Chatur Mukheshwar Ling, which Lord Chatur Mukha Brahma placed, in front of Varuna Sangameshwar.
A devotee would reach Brahma Lok by worshipping this Ling, which is also known as Chatur Mukha Prayageshwar (Kashi Khand, Chapter 97).