Current topography of Mumbai bears no resemblance to how it appeared 300 years ago. Nearly half of the main city areas and about 20% of the suburbs have been reclaimed from the shallow sea by infilling and Backbay reclamation. The raw material for this was obtained from low lying around Sion, Raoli, Sewri, Dongi-Mazgaon, Kulra, Ghatkopar, Andheri, Jogeshwari, and Marol. These hills do not exist anymore. Also, original natural water drainage have been redirected or blocked. This causes monsoon flooding in the city.
Some of the original hills in Mumbai still exist. They are Malabar Hill (Hanging Gardern), Pali Hill (Bandra), Antop Hill (Wadala), Cumbala Hill (Peddar Road), Dongri Hill (Fort). Then there is Gilbert Hill in Andheri (W) which is just a monolith structure of black basalt rock about 60m tall.
The map shows this incremental development of the city.