Dharavi is well known as one of the largest slums in the world. The slum was founded in 1880s in part because of the expulsion of factories and residents from the peninsular city center by the colonial government, and from the rural poor migrating into urban Mumbai.

Dharavi was just a marshy land at the coast of Mithi river (Mahim creek) that separated the British controlled Bombay island from Salsette island controlled by the Portuguese. In 1737, Salsette was captured by the Maratha Empire and most of the Portuguese provinces in Bombay were ceded to the Marathas (ref). Perhaps in response to that, John Horne, the governor of Bombay commissioned to build a fort at Dharavi to protect the border of Bombay from the mighty sea-faring leader of the Marathas – Kanhoji Angre. The fort is variously called as Riwa Fort, Rewah Fort or simply Kala Killa.