[GWN7]

How many sq ft is the building and what sort of foundation is it on?

For the amount of $ damage you quoted the insurance company could tear it down to the foundation and rebuild it to look exactly like it did before. Even if the foundation couldn't be certified by a engineer and they had to replace it they would be ahead. They should be able to get clearance from the city for the historical part as it would look exactly like the original building.