There's a bunker outside of Ottawa Canada, intended to house a select core of the federal government during and after a nuclear horrocaust, that is (at least) 1

There's a bunker outside of Ottawa Canada, intended to house a select core of the federal government during and after a nuclear horrocaust, that is (at least) 10 storeys of underground on a sprung foundation. It's now a museum to the cold war open to the public (and worth a visit if you're in the area) and you can actually see the massive foundation springs. Also, they run escape rooms where you're caught in the bunker during a nuclear event, which would be kind of cool.