If I ever won a big fat lottery I'd have hidden passages all over my house, and one would be like a Chinese puzzle where I had to move certain parts of a few adjoining rooms to get into the hidden one!
Basement hidden room. In MN. I would totally use this is a survival/panic room. Maybe have several hidden entrances to it around the house. Stock it with survival supplies like bottled water, shot guns, non-perishable food, first aid kit.