There are only seven houses – as opposed to apartments – in the CBD and one of the largest, at 680 square metres with a rooftop patio, is for sale.

"The Bunker", tucked behind the corner of Bourke and Queen streets in Kirks Lane, is owned by the colourful former cold-war veteran and Nauru-based businessman Desmond Oppenheimer.

Tucked away: Desmond Oppenheimer has put his city house, 6 Kirks Lane, on the market for $3 million. Credit:Peter Cox

The three levels of the converted warehouse have been carved up internally to make five bedrooms, two kitchens, an internal garden attrium, bar and lounge with a wall-size television projector.

Visitors are greeted on leaving the rattling wood cage of the old goods-style elevator on the first level by a full-size, vizored, knight's suit of shining armour.