It has all the trappings of a luxury country estate that even the pickiest homebuyer could wish for, but there are a few unexpected extras that really set this Michigan property apart from other high-end homes on the market. Now on offer for $6 million (£5m), the Doomsday-ready compound is built to offer protection should disaster strike, with a video surveillance security system throughout, a nine-acre private lake and its own underground bunker that can comfortably hold 20 people. Click on to explore...