Sonagachi, translated as Golden Tree, is the largest red-light district in Kolkata (Calcutta), India. It is an area with several hundred multi-story brothels and some 10,000 sex workers. ^ Sonagachi is located in North-Kolkata at 22°35'15''N, 88°21'35''E, near the intersection of Chittaranjan Avenue and Beadon Street, just north of the Marble Palace.