The question I have is how "historical" are we looking at? At the top end is stories we've all heard. But every building, former building, stake or ward has a story. On one hand this could quickly be filled with minutia (the Prophet slept here). On the other hand, it could be so sparse as to be of limited use. Especially if you're traveling outside of the NY to UT migration routes.
There is/was a
Church Historical Timeline application, but I'm not sure as it's active. If it is active it seems like it would be smarter to add "place" to it rather then creating another historical database.
If it's not active, what about creating a category in Google maps? Seems like that would simplify a number of things. The hard part would be getting the category added.