The unusual fort is on the cliff side near Narrow Neck on the North Shore. It's actually below ground level, so the trick for me in this sketch is to try to get that feeling of the building being in a great big hole! I'm not sure if it quite does that though.
It was originally built to defend Auckland against the Russians way back on the 1890's. Apparently there were a bunch of these built around the country, but most of them have long been demolished. As well as a number of smaller guns, there were two large guns in the cliff front from which this connected main building could supply a steady stream of ammunition. All designed to protect the Rangitoto Channel (that's Rangitoto Island in the distance) from advancing Russian vessels. Thankfully they were never actually needed!