The Sewri Fort, nestled in the crook of Mumbai Harbour, is a unique colonial British era fortification which was an important powder magazine for the British Navy. It commands a strategic location on the periphery of Mumbai Harbour and was one of the important links in the harbour's defence, preventing assaults from the Mahim Bay. It is the perfect location to explain what purpose coastal harbour fortifications have and how they were built and used. It also nestles next to some very interesting geology and some equally interesting wildlife.