Architecture preserves would be parks where endangered architecture could be erected in an environment safe from economic pressures in the form of wrecking balls. The preserves would be visitor-friendly, and would allow the threatened buildings to live and breed for the benefit of future generations.

I think there are some examples of something *like* this, commonly called "outdoor museums" or something similar, but I wonder whether those are close enough to constitute bakedness. The existing parks, for instance, seem to focus more on homes and lifestyles than on architecture per se, and are usually limited to a very narrow focus in terms of both region and era. For instance, they'd never have a Mies Wander Row and a Palladio Paddock in the same park.